API reference

Getting Started

Once you have an API key, you can make a simple request in seconds.

First request

curl "https://api.501see.app/api/v1/orgs/62-1348105" \
  -H "Authorization: Bearer YOUR_API_KEY"

Access Tiers

Free - Access to get organization by EIN with low rate limits.
Pro - Full access to every documented endpoint with increased rate limits.

Standards

Transport

API base URL: https://api.501see.app.
Responses are JSON over HTTPS.

Authentication

Send Authorization: Bearer YOUR_API_KEY on production requests.
API keys use the sk_live_ prefix.

Pagination

Use offset and limit on list endpoints.
Maximum limit is 500.
Paginated responses include data, total, offset, and limit.

Sorting

Use sort=field for ascending order.
Use sort=-field for descending order.
Each endpoint documents its supported sort keys.

Request construction

Put filters after ? and join them with &.
Repeat a parameter when the endpoint says it is repeatable.
Filing endpoints support preset=summary, preset=financials, preset=all, and fields=comma,separated,names.
fields overrides preset.

Errors

Errors use an { error: { code, message } } envelope.
Common statuses are 400, 401, 403, 404, 429, and 500.

Rate limits

Free - 2 requests per second.
Pro - 30 requests per second.

Response Schemas

These are the high-use response shapes from the public contract. The OpenAPI document contains the full schema components and examples.

PaginatedResponse<T>

Generic list envelope used by search and list endpoints. `T` is the item type, so `PaginatedResponse<OrganizationListItem>` means `data` contains organization list rows.

Field	Type	Description
data required	T[]	Returned records for the current page.
total required	integer	Total number of matching records.
offset required	integer	Current offset.
limit required	integer	Current limit.
plan	string	Present on endpoints with plan-aware field behavior.

OrganizationListItem

Slim organization row returned by /api/v1/orgs. It is the item type inside PaginatedResponse<OrganizationListItem>, not the full Organization profile.

Field	Type	Description
ein required	string	Employer Identification Number.
name required	string	Organization name.
city	string	City.
state	string	State.
zip	string	ZIP code.
ntee_code	string	NTEE code.
website	string	Website URL when available.
phone	string	Phone number when available.
formation_year	integer	Founding year.
latest_tax_period_end	date	Latest filing period end date.
total_revenue	number \| null	Latest filing revenue.
total_expenses	number \| null	Latest filing expenses.
net_assets_eoy	number \| null	Latest filing net assets at year end.
form_type	990 \| 990-EZ \| 990-PF	Latest filing form type.

Organization

Organization profile and latest filing-derived indicators.

Field	Type	Description
ein required	string	Employer Identification Number.
name required	string	Organization name.
city, state, zip, country	string	Address fields.
phone, website	string	Contact fields when available.
formation_year, domicile_state	integer/string	Formation metadata.
ntee_code, subsection	string	Classification fields.
latest_tax_period_end, latest_object_id	date/string	Latest filing references.
operating_reserve_months	number \| null	Net assets divided by monthly expenses.
revenue_growth_pct, expense_growth_pct	number \| null	Year-over-year growth metrics.
program_expense_pct, admin_expense_pct, fundraising_expense_pct	number \| null	Expense mix metrics.
contributions_pct, program_revenue_pct, investment_income_pct	number \| null	Revenue mix metrics.

Filing

Dynamic filing response. The returned fields depend on preset or fields.

Field	Type	Description
object_id, ein, form_type, tax_year	string/integer	Filing identifiers.
tax_period_begin, tax_period_end	date	Tax period dates.
org_name, org_city, org_state, org_zip, org_phone, org_website	string/number	Organization fields captured on the filing.
mission	string	Mission text when reported.
total_revenue, total_revenue_py, total_expenses, total_expenses_py	number \| null	Revenue and expense totals.
contributions, program_revenue, investment_income	number \| null	Revenue detail fields.
grants_paid, salaries_and_wages, other_expenses	number \| null	Expense detail fields.
total_assets_eoy, total_liabilities_eoy, net_assets_eoy, net_assets_boy	number \| null	Balance sheet fields.
total_employees, total_volunteers, voting_members	integer \| null	People and governance counts.
signing_officer_name, signing_officer_title	string \| null	Signing officer fields.

Officer

Officer, director, trustee, or key employee from Part VII.

Field	Type	Description
name, title	string	Person name and title.
hours_per_week	number \| null	Reported weekly hours.
compensation, other_compensation, related_compensation, benefits, total_compensation	number \| null	Compensation fields.
is_officer, is_former, is_key_employee, is_highest_compensated	boolean	Role flags from the filing.

OfficerSearchResult

Expanded officer search row with organization context and compensation fields.

Field	Type	Description
name, title	string	Person name and title.
org_name	string	Organization name.
ein	string	Organization EIN.
city, state	string	Organization location.
ntee_code	string	Organization NTEE code.
tax_year	integer	Filing tax year.
object_id	string	Filing object ID.
hours_per_week	number \| null	Reported weekly hours.
compensation, total_compensation	number \| null	Compensation fields.
total_revenue	number \| null	Organization revenue from the latest filing.
is_officer, is_key_employee, is_highest_comp, is_trustee, is_former	boolean	Role flags.

GrantSearchResult

Unified grant result across Schedule I and 990-PF sources.

Field	Type	Description
funder_ein, funder_name	string	Funder identity.
recipient_name, recipient_city, recipient_state	string	Recipient identity and location.
amount	number \| null	Grant amount.
tax_year, tax_period_begin, tax_period_end	integer/date	Filing period fields.
object_id, source	string	Source filing and source type.

SearchResult

Polymorphic search result row returned by /api/v1/search.

Field	Type	Description
type required	org \| officer \| grant	Matched entity type.
score required	number	Relevance score.
record required	object	Typed payload for the matched entity.

Export

Asynchronous CSV export job.

Field	Type	Description
id, account_id	string/integer	Export identifiers.
status	pending \| processing \| completed \| failed	Current job status.
resource_type	organizations \| grants \| officers	Exported resource type.
filters, fields	object/array	Applied filters and selected CSV fields.
row_count, file_url, file_size_bytes, error_message	varies \| null	Completion output or failure details.
notify_email, expires_at, created_at, completed_at	string/date-time \| null	Notification and lifecycle timestamps.

ErrorResponse

Standard error envelope.

Field	Type	Description
error.code required	bad_request \| not_found \| internal_error \| unauthorized \| plan_required \| rate_limited \| unavailable	Machine-readable error code.
error.message required	string	Human-readable error message.

Endpoints

Each endpoint below shows query parameters, response envelopes, and request and response examples together.

GET

Organizations

Search nonprofit organizations, fetch profiles, and navigate organization-level funder intelligence.

GET

/api/v1/orgs

List organizations

List and filter nonprofit organizations. Financial filters and sorts use the latest available filing.

Parameters

Name	In	Type	Description
offset	query	integer, default 0, min 0	Number of items to skip.
limit	query	integer, default 50, min 1, max 500	Maximum number of items to return.
sort	query	name \| -name \| state \| -state \| total_revenue \| -total_revenue \| total_expenses \| -total_expenses \| net_assets_eoy \| -net_assets_eoy	Sort field. Prefix with - for descending.
state	query	string[]	Two-letter state code. Repeat to match multiple states.
city	query	string	City substring match, case-insensitive.
ntee	query	string	NTEE code prefix. Example: K.
subsection	query	string	501(c) subsection numeric suffix. Example: 03.
name	query	string	Organization name search.
min_revenue	query	number	Minimum latest-filing total revenue.
max_revenue	query	number	Maximum latest-filing total revenue.
min_expenses	query	number	Minimum latest-filing total expenses.
max_expenses	query	number	Maximum latest-filing total expenses.
min_net_assets	query	number	Minimum latest-filing end-of-year net assets.
max_net_assets	query	number	Maximum latest-filing end-of-year net assets.
form_type	query	990 \| 990-EZ \| 990-PF	Latest filing form type.
min_program_expense_pct	query	number, 0-100	Minimum program expense ratio.
max_program_expense_pct	query	number, 0-100	Maximum program expense ratio.
min_contributions_pct	query	number, 0-100	Minimum contributions as percent of revenue.
max_contributions_pct	query	number, 0-100	Maximum contributions as percent of revenue.
min_formation_year	query	integer	Minimum founding year.
max_formation_year	query	integer	Maximum founding year.
min_employees	query	integer	Minimum employee count. Self-reported and often sparse.
max_employees	query	integer	Maximum employee count.

Example request

curl "https://api.501see.app/api/v1/orgs?name=food%20bank&state=GA&min_revenue=1000000&sort=-total_revenue&limit=10" \
  -H "Authorization: Bearer YOUR_API_KEY"

Example response

{
  "data": [
    {
      "ein": "12-3456789",
      "name": "Atlanta Food Bank",
      "city": "Atlanta",
      "state": "GA",
      "ntee_code": "K30",
      "latest_tax_period_end": "2023-12-31",
      "total_revenue": 5000000,
      "total_expenses": 4800000,
      "net_assets_eoy": 6000000,
      "form_type": "990"
    }
  ],
  "total": 1,
  "offset": 0,
  "limit": 10,
  "plan": "free"
}

Responses

Status	Schema	Description
200	PaginatedResponse<OrganizationListItem>	Paginated list of organizations.
400	ErrorResponse	Invalid parameter, sort key, filter, path value, or JSON body.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

/api/v1/orgs/{ein}

Get organization by EIN

Parameters

Name	In	Type	Description
ein required	path	string, pattern XX-XXXXXXX	Employer Identification Number. Example: 62-1348105.

Example request

curl "https://api.501see.app/api/v1/orgs/62-1348105" \
  -H "Authorization: Bearer YOUR_API_KEY"

Example response

{
  "ein": "12-3456789",
  "name": "Atlanta Food Bank",
  "city": "Atlanta",
  "state": "GA",
  "website": "https://atlantafb.org",
  "formation_year": 1990,
  "latest_tax_period_end": "2023-12-31",
  "latest_object_id": "202303559349300000",
  "operating_reserve_months": 4.8,
  "program_expense_pct": 89.4,
  "contributions_pct": 78.2
}

Responses

Status	Schema	Description
200	Organization	Organization profile, latest filing identifiers, and derived financial ratios.
404	ErrorResponse	The requested resource was not found.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

/api/v1/orgs/{ein}/recommended-funders

List recommended funders

Rank funders by how many similar organizations they fund, weighted by similarity score.

Parameters

Name	In	Type	Description
ein required	path	string	Target organization EIN.
limit	query	integer, default 20, min 1, max 100	Maximum funders to return.

Example request

curl "https://api.501see.app/api/v1/orgs/62-1348105/recommended-funders?limit=5" \
  -H "Authorization: Bearer YOUR_API_KEY"

Example response

{
  "data": [
    {
      "ein": "13-1837418",
      "name": "Community Foundation of Atlanta",
      "city": "Atlanta",
      "state": "GA",
      "ntee_code": "T31",
      "orgs_funded": 18,
      "weighted_score": 12.7,
      "total_grants": 248,
      "avg_grant": 15432.11,
      "median_grant": 10000,
      "years_active": 11,
      "top_sectors": ["K", "P", "B"]
    }
  ],
  "total": 1
}

Responses

Status	Schema	Description
200	{ data: RecommendedFunder[], total: number }	Ranked funders with overlap counts, weighted score, grant statistics, and top sectors.
401	ErrorResponse	Authentication is missing, invalid, or required for this endpoint.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

/api/v1/orgs/{ein}/grants-received

List grants received

Summarize grants received from Schedule I and 990-PF Part XV sources.

Parameters

Name	In	Type	Description
ein required	path	string, pattern XX-XXXXXXX	Recipient organization EIN.
limit	query	integer, default 20, min 1, max 100	Maximum grant records to include.

Example request

curl "https://api.501see.app/api/v1/orgs/62-1348105/grants-received?limit=5" \
  -H "Authorization: Bearer YOUR_API_KEY"

Example response

{
  "grants": [
    {
      "funder_ein": "13-1837418",
      "funder_name": "Community Foundation of Atlanta",
      "amount": 25000,
      "purpose": "Operating support",
      "tax_year": 2023
    }
  ],
  "total_grant_count": 24,
  "total_amount": 250000,
  "funder_count": 8,
  "most_recent_year": 2024
}

Responses

Status	Schema	Description
200	GrantsReceivedSummary	Recent grants plus total count, total amount, funder count, and most recent year.
400	ErrorResponse	Invalid parameter, sort key, filter, path value, or JSON body.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

/api/v1/orgs/{ein}/portfolio

Get funder giving portfolio

Precomputed foundation portfolio with yearly trends, sector mix, geography, revenue bands, and top grantees. Rebuilt monthly.

Parameters

Name	In	Type	Description
ein required	path	string	Funder EIN.

Example request

curl "https://api.501see.app/api/v1/orgs/38-1359217/portfolio"

Example response

{
  "funder_ein": "38-1359217",
  "summary": {
    "total_grants": 124,
    "total_giving": 1825000,
    "unique_recipients": 96,
    "years_active": 12
  },
  "yearly_stats": [],
  "sectors": [],
  "geography": [],
  "revenue_bands": [],
  "top_grantees": [],
  "accepts_unsolicited": true
}

Responses

Status	Schema	Description
200	FunderPortfolio	Portfolio summary, yearly stats, sectors, geography, revenue bands, and top grantees.
404	ErrorResponse	No portfolio data for this organization.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

/api/v1/orgs/{ein}/similar

List similar organizations

Find organizations similar by grant co-occurrence, NTEE code, geography, and revenue band.

Parameters

Name	In	Type	Description
ein required	path	string, pattern XX-XXXXXXX	Source organization EIN.
offset	query	integer, default 0, min 0	Number of items to skip.
limit	query	integer, default 50, min 1, max 500	Maximum number of items to return.
min_score	query	number, 0.0-1.0	Minimum composite similarity score.
signal	query	grant_cooccurrence \| ntee \| geography \| revenue_band	Limit matches to one similarity signal.

Example response

{
  "data": [
    {
      "ein": "62-1348105",
      "name": "Atlanta Food Bank",
      "city": "Atlanta",
      "state": "GA",
      "ntee_code": "K31",
      "score": 0.93,
      "signals": {
        "grant_cooccurrence": 0.88,
        "ntee": 1,
        "geography": 1
      },
      "rank": 1
    }
  ],
  "total": 1,
  "offset": 0,
  "limit": 20
}

Responses

Status	Schema	Description
200	PaginatedResponse<SimilarOrg>	Similar organizations with score, rank, and per-signal breakdown.
401	ErrorResponse	Authentication is missing, invalid, or required for this endpoint.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

Filings

Read normalized 990, 990-EZ, and 990-PF filings. Filing responses are dynamic maps driven by presets or explicit fields.

GET

/api/v1/orgs/{ein}/filings

List filings for an organization

Parameters

Name	In	Type	Description
ein required	path	string, pattern XX-XXXXXXX	Organization EIN.
offset	query	integer, default 0, min 0	Number of items to skip.
limit	query	integer, default 50, min 1, max 500	Maximum number of items to return.
preset	query	summary \| financials \| all, default summary	Field preset for filing responses. Ignored when fields is provided.
fields	query	comma-separated string	Specific filing fields to return. Overrides preset. Example: total_revenue,total_expenses,mission.
sort	query	tax_year \| -tax_year \| total_revenue \| -total_revenue \| total_expenses \| -total_expenses, default -tax_year	Sort field. Prefix with - for descending.
tax_year	query	integer	Exact tax year.
form_type	query	990 \| 990EZ \| 990PF	Filing form type.

Example request

curl "https://api.501see.app/api/v1/orgs/62-1348105/filings?preset=financials&sort=-tax_year&limit=5" \
  -H "Authorization: Bearer YOUR_API_KEY"

Example response

{
  "data": [
    {
      "object_id": "202303559349300000",
      "ein": "62-1348105",
      "form_type": "990",
      "tax_year": 2023,
      "total_revenue": 5000000,
      "total_expenses": 4800000,
      "mission": "To reduce hunger in our community."
    }
  ],
  "total": 1,
  "offset": 0,
  "limit": 5,
  "plan": "free"
}

Responses

Status	Schema	Description
200	PaginatedResponse<Filing>	Paginated filing objects with fields selected by preset or fields.
400	ErrorResponse	Invalid parameter, sort key, filter, path value, or JSON body.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

/api/v1/orgs/{ein}/filings/latest

Get latest filing

Parameters

Name	In	Type	Description
ein required	path	string, pattern XX-XXXXXXX	Organization EIN.
preset	query	summary \| financials \| all, default summary	Field preset for filing responses. Ignored when fields is provided.
fields	query	comma-separated string	Specific filing fields to return. Overrides preset. Example: total_revenue,total_expenses,mission.

Example request

curl "https://api.501see.app/api/v1/orgs/62-1348105/filings/latest?fields=tax_year,total_revenue,total_expenses,mission" \
  -H "Authorization: Bearer YOUR_API_KEY"

Example response

{
  "object_id": "202303559349300000",
  "ein": "62-1348105",
  "form_type": "990",
  "tax_year": 2023,
  "total_revenue": 5000000,
  "total_expenses": 4800000,
  "mission": "To reduce hunger in our community."
}

Responses

Status	Schema	Description
200	Filing	Most recent filing by tax year.
404	ErrorResponse	The requested resource was not found.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

/api/v1/filings/{object_id}

Get filing by object ID

Parameters

Name	In	Type	Description
object_id required	path	string	IRS e-file object ID.
preset	query	summary \| financials \| all, default summary	Field preset for filing responses. Ignored when fields is provided.
fields	query	comma-separated string	Specific filing fields to return. Overrides preset. Example: total_revenue,total_expenses,mission.

Example response

{
  "object_id": "202303559349300000",
  "ein": "62-1348105",
  "form_type": "990",
  "tax_year": 2023,
  "mission": "To reduce hunger in our community."
}

Responses

Status	Schema	Description
200	Filing	One normalized filing object.
404	ErrorResponse	The requested resource was not found.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

Officers

Search officers, directors, trustees, key employees, and compensation benchmarks.

GET

/api/v1/officers

Search officers across all filings

Defaults to paid staff with non-zero compensation. Compensation fields are plan-aware.

Parameters

Name	In	Type	Description
offset	query	integer, default 0, min 0	Number of items to skip.
limit	query	integer, default 50, min 1, max 500	Maximum number of items to return.
sort	query	compensation \| -compensation \| tax_year \| -tax_year \| name \| -name, default -compensation	Sort field. Prefix with - for descending.
name	query	string	Officer name search.
title	query	string	Free-text title keyword.
role	query	development \| finance \| executive \| programs \| operations \| marketing \| hr \| legal	Curated role group mapped from titles.
role_type	query	staff \| board \| former \| all, default staff	Position type filter.
ein	query	string	Organization EIN.
state	query	string	Organization state.
ntee	query	string	Organization NTEE code or major-group prefix.
min_revenue	query	number	Minimum organization revenue.
max_revenue	query	number	Maximum organization revenue.
min_year	query	integer	Minimum tax year.
max_year	query	integer	Maximum tax year.
min_compensation	query	number	Minimum total compensation.
max_compensation	query	number	Maximum total compensation.

Example request

curl "https://api.501see.app/api/v1/officers?role=development&state=GA&min_revenue=500000&sort=-compensation" \
  -H "Authorization: Bearer YOUR_API_KEY"

Example response

{
  "data": [
    {
      "name": "Jordan Smith",
      "title": "Development Director",
      "org_name": "Atlanta Food Bank",
      "ein": "62-1348105",
      "city": "Atlanta",
      "state": "GA",
      "tax_year": 2023,
      "object_id": "202303559349300000",
      "compensation": 125000,
      "total_compensation": 131500,
      "total_revenue": 5000000,
      "is_officer": true,
      "is_key_employee": false,
      "is_highest_comp": false,
      "is_trustee": false,
      "is_former": false
    }
  ],
  "total": 1,
  "offset": 0,
  "limit": 50,
  "plan": "free"
}

Responses

Status	Schema	Description
200	PaginatedResponse<OfficerSearchResult>	Officer search results with filing and organization context.
400	ErrorResponse	Invalid parameter, sort key, filter, path value, or JSON body.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

/api/v1/filings/{object_id}/officers

List officers for a filing

Parameters

Name	In	Type	Description
object_id required	path	string	IRS e-file object ID.
offset	query	integer, default 0, min 0	Number of items to skip.
limit	query	integer, default 50, min 1, max 500	Maximum number of items to return.

Example request

curl "https://api.501see.app/api/v1/filings/202303559349300000/officers?limit=5" \
  -H "Authorization: Bearer YOUR_API_KEY"

Example response

{
  "data": [
    {
      "name": "Jordan Smith",
      "title": "Development Director",
      "hours_per_week": 40,
      "compensation": 125000,
      "other_compensation": 3000,
      "related_compensation": 1500,
      "benefits": 2000,
      "is_officer": true,
      "is_former": false,
      "is_key_employee": false,
      "is_highest_compensated": false,
      "total_compensation": 131500
    }
  ],
  "total": 1,
  "offset": 0,
  "limit": 50,
  "plan": "free"
}

Responses

Status	Schema	Description
200	PaginatedResponse<Officer>	Part VII officers, directors, trustees, and key employees.
400	ErrorResponse	Invalid parameter, sort key, filter, path value, or JSON body.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

/api/v1/compensation-benchmark

Compensation percentile benchmarks

Parameters

Name	In	Type	Description
role required	query	string	Role group key. Example: executive, development, finance, programs.
ntee	query	string	NTEE major category letter.
state	query	string	Two-letter US state code.
min_revenue	query	number	Minimum organization revenue.
max_revenue	query	number	Maximum organization revenue.

Example response

{
  "count": 124,
  "p25": 82000,
  "median": 114000,
  "p75": 156000,
  "mean": 118750
}

Responses

Status	Schema	Description
200	{ count, p25, median, p75, mean }	Compensation percentile statistics for matched officer records.
400	ErrorResponse	Invalid parameter, sort key, filter, path value, or JSON body.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

Grants

Search grants across Schedule I and 990-PF Part XV. Also list grants from individual filings.

GET

/api/v1/grants

Search grants across all filings

Parameters

Name	In	Type	Description
offset	query	integer, default 0, min 0	Number of items to skip.
limit	query	integer, default 50, min 1, max 500	Maximum number of items to return.
sort	query	amount \| -amount \| tax_year \| -tax_year \| funder_name \| -funder_name \| recipient_name \| -recipient_name, default -amount	Sort field. Prefix with - for descending.
funder_ein	query	string	Funder EIN.
funder_name	query	string	Funder organization name search.
funder_ntee	query	string	Funder NTEE major category.
funder_state	query	string[]	Funder home state. Repeat for multiple states.
recipient_ntee	query	string	Recipient NTEE major category or full code.
recipient_ein	query	string	Recipient EIN.
similar_to	query	string	Filter to funders that also fund organizations similar to this EIN.
recipient_name	query	string	Recipient name search.
min_amount	query	number	Minimum grant amount.
max_amount	query	number	Maximum grant amount.
state	query	string[]	Recipient state. Repeat for multiple states.
tax_year	query	integer	Exact tax year.
min_year	query	integer	Minimum tax year, inclusive.
max_year	query	integer	Maximum tax year, inclusive.
source	query	990 \| 990-PF	Grant source.
purpose	query	string	Full-text search against grant purpose.
query	query	string	Keyword search across recipient name and grant purpose.

Example request

curl "https://api.501see.app/api/v1/grants?state=TN&min_amount=10000&source=990-PF&limit=5" \
  -H "Authorization: Bearer YOUR_API_KEY"

Example response

{
  "data": [
    {
      "funder_ein": "38-1359217",
      "funder_name": "Smith Family Foundation",
      "recipient_name": "Community Food Project",
      "recipient_city": "Nashville",
      "recipient_state": "TN",
      "recipient_ein": "62-1348105",
      "amount": 25000,
      "tax_year": 2023,
      "tax_period_begin": "2023-01-01",
      "tax_period_end": "2023-12-31",
      "object_id": "202303559349300000",
      "source": "990-PF",
      "purpose": "Operating support"
    }
  ],
  "total": 1,
  "offset": 0,
  "limit": 5,
  "plan": "free"
}

Responses

Status	Schema	Description
200	PaginatedResponse<GrantSearchResult>	Unified grant search results with funder, recipient, amount, tax year, source, and purpose fields.
400	ErrorResponse	Invalid parameter, sort key, filter, path value, or JSON body.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

/api/v1/filings/{object_id}/grants

List Schedule I grants for a filing

Parameters

Name	In	Type	Description
object_id required	path	string	IRS e-file object ID.
offset	query	integer, default 0, min 0	Number of items to skip.
limit	query	integer, default 50, min 1, max 500	Maximum number of items to return.

Example response

{
  "data": [
    {
      "recipient_name": "Community Food Project",
      "recipient_city": "Nashville",
      "recipient_state": "TN",
      "recipient_ein": "62-1348105",
      "cash_amount": 25000,
      "purpose": "Operating support"
    }
  ],
  "total": 1,
  "offset": 0,
  "limit": 50,
  "plan": "free"
}

Responses

Status	Schema	Description
200	PaginatedResponse<Grant>	Schedule I grants paid from a 990 filing.
400	ErrorResponse	Invalid parameter, sort key, filter, path value, or JSON body.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

Private Foundations

Search private foundations, read 990-PF-specific filing data, and list Part XV grants paid.

GET

/api/v1/foundations

Search private foundations by giving behavior

Backed by precomputed monthly funder portfolio aggregations. Purpose search falls back to raw grant purpose and grantee names when needed.

Parameters

Name	In	Type	Description
name	query	string	Foundation name keyword.
state	query	string	Foundation home state. Repeatable.
city	query	string	Foundation home city.
ntee	query	string	Foundation NTEE prefix. Repeatable.
funder_sector	query	string	NTEE major letter of sectors they fund. Repeatable.
funder_geo_state	query	string	States where the foundation gives grants. Repeatable.
min_avg_grant	query	number	Minimum average grant amount.
max_avg_grant	query	number	Maximum average grant amount.
min_median_grant	query	number	Minimum median grant amount.
max_median_grant	query	number	Maximum median grant amount.
min_total_grants	query	integer	Minimum total grant count.
min_years_active	query	integer	Minimum years with grant activity.
min_formation_year	query	integer	Minimum formation year.
max_formation_year	query	integer	Maximum formation year.
min_revenue	query	number	Minimum latest-year total revenue, with 990/990-PF/BMF fallback.
max_revenue	query	number	Maximum latest-year total revenue, with 990/990-PF/BMF fallback.
min_expenses	query	number	Minimum latest-year total expenses.
max_expenses	query	number	Maximum latest-year total expenses.
min_assets	query	number	Minimum latest-year total assets.
max_assets	query	number	Maximum latest-year total assets.
min_net_assets	query	number	Minimum latest-year net assets.
max_net_assets	query	number	Maximum latest-year net assets.
purpose	query	string	Full-text keyword search against portfolio profile, raw grant purpose, and grantee-name text.
debug_scores	query	boolean	Include lexical, semantic, and blended ranking scores.
hide_preselected	query	boolean	Exclude funders whose latest 990-PF says contributors are preselected.
sort	query	name \| total_grants \| avg_grant \| years_active \| total_giving, optional - prefix	Sort field.
limit	query	integer, default 25, min 1, max 500	Maximum records to return.
offset	query	integer, default 0, min 0	Number of records to skip.

Example request

curl "https://api.501see.app/api/v1/foundations?state=CA&funder_sector=B&min_total_grants=100&hide_preselected=true" \
  -H "Authorization: Bearer YOUR_API_KEY"

Example response

{
  "data": [
    {
      "ein": "38-1359217",
      "name": "Smith Family Foundation",
      "city": "San Francisco",
      "state": "CA",
      "ntee_code": "T20",
      "total_grants": 124,
      "avg_grant": 14750,
      "median_grant": 10000,
      "years_active": 12,
      "accepts_unsolicited": true
    }
  ],
  "total": 1,
  "offset": 0,
  "limit": 25,
  "plan": "free"
}

Responses

Status	Schema	Description
200	PaginatedResponse<FoundationResult>	Private foundation results with portfolio fields and application-status signals.
400	ErrorResponse	Invalid parameter, sort key, filter, path value, or JSON body.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

/api/v1/filings/{object_id}/pf

Get 990-PF financials for a filing

Parameters

Name	In	Type	Description
object_id required	path	string	IRS e-file object ID.
preset	query	summary \| financials \| all, default summary	Field preset for filing responses. Ignored when fields is provided.
fields	query	comma-separated string	Specific filing fields to return. Overrides preset. Example: total_revenue,total_expenses,mission.

Example request

curl "https://api.501see.app/api/v1/filings/202303559349300000/pf?fields=tax_year,total_revenue,total_expenses,net_assets_eoy" \
  -H "Authorization: Bearer YOUR_API_KEY"

Example response

{
  "object_id": "202303559349300000",
  "ein": "38-1359217",
  "form_type": "990-PF",
  "tax_year": 2023,
  "total_revenue": 2500000,
  "total_expenses": 1800000,
  "net_assets_eoy": 12000000,
  "contributors_preselected": true
}

Responses

Status	Schema	Description
200	PFFiling	990-PF-specific financial data for one filing.
404	ErrorResponse	The requested resource was not found.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

/api/v1/filings/{object_id}/pf/grants

List Part XV foundation grants paid

Parameters

Name	In	Type	Description
object_id required	path	string	IRS e-file object ID.
offset	query	integer, default 0, min 0	Number of items to skip.
limit	query	integer, default 50, min 1, max 500	Maximum number of items to return.

Example response

{
  "data": [
    {
      "recipient_name": "Community Food Project",
      "recipient_city": "Nashville",
      "recipient_state": "TN",
      "recipient_ein": "62-1348105",
      "amount": 25000,
      "purpose": "Operating support",
      "relationship": "independent",
      "status": "paid"
    }
  ],
  "total": 1,
  "offset": 0,
  "limit": 50,
  "plan": "free"
}

Responses

Status	Schema	Description
200	PaginatedResponse<PFGrant>	990-PF Part XV grants paid.
400	ErrorResponse	Invalid parameter, sort key, filter, path value, or JSON body.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

Search

Full-text search across organizations, officers, and grants.

GET

/api/v1/search

Full-text search

Parameters

Name	In	Type	Description
offset	query	integer, default 0, min 0	Number of items to skip.
limit	query	integer, default 50, min 1, max 500	Maximum number of items to return.
query required	query	string	Search query string.
type	query	org \| officer \| grant	Restrict results to one entity type.

Example response

{
  "data": [
    {
      "type": "org",
      "score": 0.98,
      "record": {
        "ein": "62-1348105",
        "name": "Atlanta Food Bank",
        "city": "Atlanta",
        "state": "GA"
      }
    },
    {
      "type": "officer",
      "score": 0.89,
      "record": {
        "name": "Jordan Smith",
        "title": "Development Director",
        "ein": "62-1348105",
        "org_name": "Atlanta Food Bank"
      }
    }
  ],
  "total": 2,
  "offset": 0,
  "limit": 50,
  "plan": "free"
}

Responses

Status	Schema	Description
200	PaginatedResponse<SearchResult>	Polymorphic search results sorted by relevance.
400	ErrorResponse	Invalid parameter, sort key, filter, path value, or JSON body.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

POST

Exports

Create and manage asynchronous CSV export jobs for larger result sets.

POST

/api/v1/exports

Create a CSV export job

Create an asynchronous export job. Poll GET /api/v1/exports/{id} until status is completed, then download file_url.

Request body

Field	Type	Description
resource_type required	organizations \| grants \| officers	Resource to export.
filters	object	Same filter parameters as the corresponding list or search endpoint.
notify_email	string	Optional completion notification email.

Example request

curl "https://api.501see.app/api/v1/exports" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"resource_type":"grants","filters":{"state":"TN","min_amount":10000}}'

Example response

{
  "id": "exp_01J3NQ2Z2T7B7R3Y1QW8T8G5F2",
  "account_id": "acct_01J3NQ0G3P4V8C7H2K6W1M9D8X",
  "status": "pending",
  "resource_type": "grants",
  "filters": {
    "state": "TN",
    "min_amount": 10000
  },
  "fields": [],
  "created_at": "2026-06-03T12:00:00Z"
}

Responses

Status	Schema	Description
202	Export	Export job accepted and queued.
400	ErrorResponse	Invalid parameter, sort key, filter, path value, or JSON body.
401	ErrorResponse	Authentication is missing, invalid, or required for this endpoint.
403	ErrorResponse	The authenticated caller does not have access to this operation.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

/api/v1/exports

List exports

Example request

curl "https://api.501see.app/api/v1/exports" \
  -H "Authorization: Bearer YOUR_API_KEY"

Example response

{
  "data": [
    {
      "id": "exp_01J3NQ2Z2T7B7R3Y1QW8T8G5F2",
      "account_id": "acct_01J3NQ0G3P4V8C7H2K6W1M9D8X",
      "status": "completed",
      "resource_type": "grants",
      "row_count": 124,
      "file_url": "https://files.501see.app/exports/exp_01J3NQ2Z2T7B7R3Y1QW8T8G5F2.csv",
      "created_at": "2026-06-03T12:00:00Z",
      "completed_at": "2026-06-03T12:02:11Z"
    }
  ]
}

Responses

Status	Schema	Description
200	{ data: Export[] }	Exports for the authenticated account.
401	ErrorResponse	Authentication is missing, invalid, or required for this endpoint.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

GET

/api/v1/exports/{id}

Get export job by ID

Parameters

Name	In	Type	Description
id required	path	string	Export job UUID.

Example request

curl "https://api.501see.app/api/v1/exports/exp_01J3NQ2Z2T7B7R3Y1QW8T8G5F2" \
  -H "Authorization: Bearer YOUR_API_KEY"

Example response

{
  "id": "exp_01J3NQ2Z2T7B7R3Y1QW8T8G5F2",
  "account_id": "acct_01J3NQ0G3P4V8C7H2K6W1M9D8X",
  "status": "completed",
  "resource_type": "grants",
  "row_count": 124,
  "file_url": "https://files.501see.app/exports/exp_01J3NQ2Z2T7B7R3Y1QW8T8G5F2.csv",
  "created_at": "2026-06-03T12:00:00Z",
  "completed_at": "2026-06-03T12:02:11Z"
}

Responses

Status	Schema	Description
200	Export	Export job status and file details.
401	ErrorResponse	Authentication is missing, invalid, or required for this endpoint.
404	ErrorResponse	The requested resource was not found.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

DELETE

/api/v1/exports/{id}

Delete export job

Parameters

Name	In	Type	Description
id required	path	string	Export job UUID.

Example request

curl -X DELETE "https://api.501see.app/api/v1/exports/exp_01J3NQ2Z2T7B7R3Y1QW8T8G5F2" \
  -H "Authorization: Bearer YOUR_API_KEY"

Example response

{
  "status": "ok"
}

Responses

Status	Schema	Description
200	{ status: "ok" }	Export job deleted.
401	ErrorResponse	Authentication is missing, invalid, or required for this endpoint.
404	ErrorResponse	The requested resource was not found.
429	ErrorResponse	Rate limit exceeded. Retry with backoff.

Integrations

These integration surfaces are designed for both human workflows and agent workflows. Start with the OpenAPI schema when you want a formal contract, then use MCP for tool-driven automation.

OpenAPI schema

Use the OpenAPI document for code generation, SDKs, and tools that need a machine-readable contract.

Download OpenAPI schema

Remote MCP configuration

{
  "mcpServers": {
    "501see": {
      "type": "sse",
      "url": "https://api.501see.app/mcp",
      "headers": {
        "Authorization": "Bearer YOUR_API_KEY"
      }
    }
  }
}