Is there a free alternative to the Candid API?

Plinth's grants API is free with a key at 50 calls a month, covering 205,000 US grantmaking foundations and 17.9 million grants from IRS 990, 990-EZ and 990-PF filings, with traversal in both directions. Candid's grant and nonprofit data APIs are paid — the Grants API starts at $6,000 a year — though Candid offers a 30-day free trial on request and lists its Demographics and Taxonomy APIs at no fee. ProPublica's Nonprofit Explorer API is also free but returns Form 990 summaries with no grant-level records.

Can I point an existing Candid client at Plinth?

It is close, but not drop-in, and anyone telling you otherwise has not checked. The parameter vocabulary largely matches — recip_id, subject and year mean the same thing on both. Three things always change: the authentication header (Candid uses Subscription-Key, we use X-API-Key or a Bearer token), the amount filters (Candid uses min_amt and max_amt), and the compliance path (our /compliance, not charitycheck). Candid moved Essentials and Premier to v4 in March 2026, and we have not been able to diff v4 responses field by field, so budget time to check response fields against your own usage.

What are the rate limits?

A free Plinth key allows 50 calls a month; paid plans raise it for volume. Every response carries your remaining allowance in the X-Calls-Remaining header so you can back off before hitting the limit. Candid's developer portal documents a rate-limits topic, but we could not retrieve published numeric limits, so check with Candid directly rather than relying on a figure from us.

For developers

A free alternative to the Candid API

Plinth publishes a JSON grants API over 205,000 US grantmaking foundations and 17.9 million grants, read from IRS Form 990, 990-EZ and 990-PF filings. It is free with a key at 50 calls a month, and it deliberately follows the parameter vocabulary of existing grant-data APIs, so porting a client is mostly mechanical.

It is nota drop-in replacement, and this page is specific about why. Candid figures below were read from Candid’s own developer portal and pricing pages on 12 August 2026.

In one screen

Plinth's grants API is free with a key at 50 calls a month, covering 205,000 funders and 17.9 million grants.
Candid's Grants API starts at $6,000 a year, Essentials at $4,800 and Premier at $9,900, with a 30-day free trial on request; its Demographics and Taxonomy APIs are listed at no fee.
The parameter vocabulary is close: recip_id, subject, year and amount filters carry the same meaning on both.
Two changes a migration always needs: the auth header, and the amount filter parameters.
Both APIs traverse in both directions — funder to grantee and grantee to funder.
Plinth adds a SQL endpoint and a plain-English query interface over the whole corpus; Candid adds compliance-grade Charity Check, enriched Premier profiles and news, which Plinth has no equivalent for.

What changes in a migration

Three edits cover most clients. The first two are unavoidable.

1 · The authentication header

Candid authenticates with Subscription-Key. We accept X-API-Key or an Authorization: Bearer token. Keys start plinth_sk_ and are secrets — keep them server-side.

# before
curl -H 'Subscription-Key: $CANDID_KEY' \
  'https://api.candid.org/grants/v1/transactions?recip_id=13-1837418'

# after
curl -H 'X-API-Key: $PLINTH_API_KEY' \
  'https://data.useplinth.com/api/grants/transactions?recip_id=13-1837418'

2 · Amount filters

Candid filters grant size with min_amt and max_amt. Check how your client builds amount ranges before assuming a single amount parameter carries over.

3 · The compliance path

Our compliance lookup is /compliance, not charitycheck. Read the caveat below before treating this as a like-for-like swap.

Endpoint mapping

Candid	Plinth	Notes
Grants API /transactions	/api/grants/transactions	Individual grant rows. Same shape of question.
Grants API /funders	/api/grants/funders	Funder-side aggregates — who gave, how much.
Grants API /recipients	/api/grants/recipients	Recipient-side lookup. Both support grantee → funders traversal.
Grants API /summary	/api/grants/summary	Aggregate statistics over a filtered set.
Essentials API (v4)	/api/essentials/{ein}	Organization lookup. Candid's covers 1.9M profiles with enrichment collected directly from nonprofits; ours is filing-derived.
Premier API (v4)	/api/premier/{ein}	Fuller organization record. Candid states 760+ additional fields — not an equivalent, see below.
Charity Check API	/api/compliance/{ein}	The one rename. NOT equivalent for regulated use — see what is not equivalent.
No equivalent	/api/sql	Arbitrary analytical queries over the whole corpus.
No equivalent	/api/analyze	Ask a question in plain English; get a sourced answer and the query that produced it.

Candid endpoint names and parameters read from the Grants API reference and authentication docs, 2026-08-12.

What is not equivalent

Compliance verification.Candid’s Charity Check produces time-stamped documentation for audit records. If you need verified charitable status for a regulated workflow — grant disbursement, donation processing, KYC — use Candid. Our /compliance endpoint reports filing-derived status and is not a substitute for that.

Enrichment beyond the filings. Candid states Premier carries 760+ additional fields, much of it collected directly from nonprofits through profile claiming and Seals of Transparency. That data does not exist in IRS filings, so we do not have it at any price.

Products with no counterpart.News, Taxonomy, Demographics, Nonprofit Eligibility and Open RFP Opportunities. Candid’s Demographics and Taxonomy APIs are listed at no fee, so “free API” is not by itself a reason to switch.

Corpus size. Candid states 29 million grants and 304,000 funder profiles, against our 17.9 million grants and 205,000 funders. If coverage is the binding constraint, Candid has more.

What we could not verify. Candid released Essentials and Premier v4 on 25 March 2026. We were unable to retrieve a published OpenAPI document to diff v4 responses field by field, so treat the organization-lookup mapping above as a starting point and check response fields against your own usage rather than trusting it wholesale.

What you get that Candid has no counterpart for

A SQL endpoint. /api/sql runs analytical queries directly against the corpus, so questions that would take many paged REST calls become one query.

Plain-English querying. /api/analyze takes a question, writes and runs the query, and returns a sourced answer with the SQL it used. Also available in the browser at /analyze.

Layers computed across the whole corpus — co-funder overlap strength, portfolio clustering, board interlocks from Form 990 Part VII, and federal plus nine-state government funding joined to the same organizations.

Where Plinth is the wrong tool

The IRS filing lag is 12 to 24 months. For what a foundation is funding this quarter, a platform that tracks live opportunities will beat us — Instrumentl tracks active RFPs and deadlines, and Impala refreshes most sources weekly.
We cover electronic filers. Organizations that file on paper, and those too small to file a full return, are absent or thin.
Entity resolution is deterministic and tuned to drop rather than guess, so the graph is high-precision and knowingly incomplete. A grant we cannot confidently resolve to an EIN is left out rather than attached to the wrong organization.
Funder pages detail the top 2,000 grantees by value and summarise the tail. For a donor-advised fund sponsor with 100,000 grantees, the page is a summary, not the full ledger.
We do not do grant-pipeline management: no deadline tracking, no application workflow, no reporting calendar. If that is the job, Instrumentl is built for it and we are not.
Candid and Impala both publish larger cumulative grant counts than ours, and Candid has been the sector's reference source since long before we existed.

Get a key

Free, no card, about a minute: generate an API key. Full reference at /developers. If you are weighing the platforms rather than the APIs, Plinth vs Candid covers the product comparison, and the comparison hub covers the rest of the market.

Questions and answers

Is there a free alternative to the Candid API?: Plinth's grants API is free with a key at 50 calls a month, covering 205,000 US grantmaking foundations and 17.9 million grants from IRS 990, 990-EZ and 990-PF filings, with traversal in both directions. Candid's grant and nonprofit data APIs are paid — the Grants API starts at $6,000 a year — though Candid offers a 30-day free trial on request and lists its Demographics and Taxonomy APIs at no fee. ProPublica's Nonprofit Explorer API is also free but returns Form 990 summaries with no grant-level records.
Can I point an existing Candid client at Plinth?: It is close, but not drop-in, and anyone telling you otherwise has not checked. The parameter vocabulary largely matches — recip_id, subject and year mean the same thing on both. Three things always change: the authentication header (Candid uses Subscription-Key, we use X-API-Key or a Bearer token), the amount filters (Candid uses min_amt and max_amt), and the compliance path (our /compliance, not charitycheck). Candid moved Essentials and Premier to v4 in March 2026, and we have not been able to diff v4 responses field by field, so budget time to check response fields against your own usage.
What is not equivalent?: Several things, and they matter. Charity Check produces time-stamped compliance documentation for audit records — if you need verified charitable status for a regulated workflow, use Candid, not us. Premier carries hundreds of enrichment fields collected directly from nonprofits that simply do not exist in filings. Candid also offers News, Taxonomy, Demographics and RFP APIs we have no counterpart for. And Candid's corpus is larger: it states 29 million grants against our 17.9 million.
What are the rate limits?: A free Plinth key allows 50 calls a month; paid plans raise it for volume. Every response carries your remaining allowance in the X-Calls-Remaining header so you can back off before hitting the limit. Candid's developer portal documents a rate-limits topic, but we could not retrieve published numeric limits, so check with Candid directly rather than relying on a figure from us.

How this comparison was made.Every figure attributed to another company was read from that company’s own public pages on 12 August 2026, and each cell links to the page it came from. Review sites, software directories and comparison blogs were not used as sources. Where we could not confirm a capability from a vendor’s own documentation, the cell reads “not publicly documented” — that means we did not find it, not that it is absent. Pricing is the published list price and excludes discounts and custom terms. Product names are used only to identify the products compared. Tell us if something here is wrong and we will correct it.