Head to head · Market prices · October 2026 research run

Intrinio vs Massive (formerly Polygon.io)

Massive (formerly Polygon.io) scores 73.1 (BB) on agent readiness against Intrinio's 54.2 (C), and leads in 5 of 7 scored categories. Intrinio leads on reliability. Both do market prices. Massive (formerly Polygon.io) accepts x402. Intrinio doesn't.

Best financial market data APIs for AI agents · All 55 markets comparisons

Which one, for what

Intrinio C

Best for An agent doing US equity, options and fundamentals research on a paid plan that wants one vendor for prices, filings, estimates and an OAuth MCP server.

Ahead on

  • Reliability, 83 against 78

Watch for

The API key is documented as api_key in the query string as the first option, with no scopes, rotation or expiry found

Massive (formerly Polygon.io) BB

Best for Agents that need US equities, options or futures data with real history, and the only listing here selling US stock data over x402.

Ahead on

  • Schema & documentation, 89 against 43
  • Agent ergonomics, 78 against 70
  • Payments & pricing, 90 against 20
  • Maintenance & community, 82 against 70
  • Transparency & trust, 67 against 51

Also in its favour

  • Agent-ready, a grade of BB or better
  • An agent can pay per call over x402, with no account

Watch for

14 partial incidents from 3 August to 1 November 2026, mostly stale or missing data on stock aggregates and quotes

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Payments & pricing Massive (formerly Polygon.io) +70

Intrinio 20

No x402, MPP or L402 (0). Plan prices are public without a login, $150, $333 rising to $999, and $1,250 and up, with no per-call price (10). Both self-serve plans say a free trial is available, and the trial length and card requirement were not found on the pricing, plan or terms pages, since the plan pages are drawn by script (10 of 20). A person signs up in a browser; no key API was found (0). Total 20.

Massive (formerly Polygon.io) 90

x402 on its own domain at agent.massive.com since 1 September, but only 23 US stock routes. Options, indices, forex, crypto, futures, tick data and streaming still need a key (30 of 40). $0.01 a route on Agentic.Market, which the docs link to, and plan prices on massive.com/pricing, all without a login (20). Free Basic plan at 5 calls a minute with end-of-day data. The pricing page doesn't say a card is needed (20). An agent with a funded Base wallet can pay with no account (20).

Schema & documentation Massive (formerly Polygon.io) +46

Intrinio 43

No OpenAPI document was found. The SDKs are generated from a spec that declares API version 2.135.4, but the spec itself isn't published, and the MCP server's tool definitions aren't in any public source (5 of 25). docs.intrinio.com/llms.txt and intrinio.com/llms.txt return 404, and there are no Markdown pages (0 of 10). Each endpoint page states what it returns with its parameters, with little on when not to use a call (12 of 20). Parameters are typed, with required ones marked and allowed values in prose (9 of 15). Code samples in six languages on every endpoint, and a response codes page that lists codes without a body format (10 of 15). The v2 path is versioned, but the version history lists 2.0.0 to 2.6.2 with no dates and is out of step with the SDK's API version (7 of 15). Total 43.

Massive (formerly Polygon.io) 89

OpenAPI document at api.massive.com/openapi (OpenAPI 3.0.3, 148 paths) with enums such as timespan and sort, and 400, 401 and 404 responses defined (25). llms.txt at massive.com/docs/rest/llms.txt indexing about 160 endpoint pages (10). One-line descriptions per endpoint in the index, longer ones in the reference, with little on when not to use a call (14 of 20). Typed path and query parameters with enums and required fields (13 of 15). Examples in the docs and error responses in the spec, though the llms.txt says nothing about error shapes (12 of 15). Versioned paths from /v1 to /v3 and a dated public changelog (15).

Transparency & trust Massive (formerly Polygon.io) +16

Intrinio 51

A closed service under terms effective 3 September 2026 that are clear on personal, internal and commercial use and name Intrinio, Inc. (15 of 30). The privacy policy is dated 30 June 2018, names no retention periods, subprocessors or DPA, and says only that connection details may be retained; the terms require deletion within 30 days of termination with an officer's certification (8 of 30). No deprecation policy, and the version history has no dates (3 of 20). Data is processed in the United States; no subprocessor list (5 of 20). Total 31.

Massive (formerly Polygon.io) 67

Closed service under business terms last updated 6 October 2026, Massive.com, Inc. under Georgia law, which now also cover pay-per-request purchases without an account. The MCP server and clients are MIT (15). Privacy policy last updated 22 March 2024, with retention 'as long as we are providing the Services' and no periods. The business terms require deleting data on termination. No DPA found (12 of 30). Dated sunsets in the changelog. The terms let Massive change the Services at its discretion, with a 30-day route to report a change that materially degrades a subscribed service (10 of 20). Stripe, Google and Hotjar are named, and data may sit 'in the United States and locations around the world'. No subprocessor list (8 of 20).

Maintenance & community Massive (formerly Polygon.io) +12

Intrinio 70

The six real-time websocket SDK repositories were pushed between 22 and 29 October 2026, and the MCP server is labelled New on the vendor's page (30). The last tagged release found is intrinio-sdk 7.2.0 on PyPI on 27 May 2026, following 7.0.0 on 2 March and 7.1.0 on 24 March; the October pushes have no tags or dated changelog entries, and the API version history carries no dates (10 of 20). Support is live chat through HubSpot, an AI chat and support@intrinio.com, with a status page; GitHub issue activity was not read (8 of 15). Official SDKs are current in six languages (15). The Python SDK is generated by swagger-codegen with CI not checked (7 of 10). Total 70.

Massive (formerly Polygon.io) 82

Newest changelog entry 2026-10-28, new Insider Trading Activity and Insider Holdings endpoints (30). Changelog entries on 25 August, 1 September, 22 September, 2 October, 16 October and 28 October, six in 90 days, besides client releases (20). Public changelog and a support channel. We couldn't read GitHub issue activity in this run (10 of 15). Official clients are current, with Python v2.9.0 on 2026-10-16 and v2.9.1 on 2026-10-25, Go v3.5.0, v3.6.0 and v3.7.0 between 20 and 27 October and JavaScript v10.8.0 on 2026-09-17, each regenerated from the OpenAPI spec (15). The MCP and client repos run CI. The MCP server repository is still at v0.10.0 of 2026-05-05 and its README still calls the project experimental (7 of 10).

Agent ergonomics Massive (formerly Polygon.io) +8

Intrinio 70

page_size from 100 up to 10,000 sizes a response, and the MCP server batches ticker lists, but there is no field selection (15 of 25). next_page tokens, date and symbol filters on the data endpoints (18 of 20). Response codes are documented, 403 for an unsubscribed feed and 429 with a limit explanation, with no error body format or error code reference (10 of 20). Every call is a read and the vendor says the MCP server writes nothing back, but no readOnlyHint or safe-retry guidance was found (12 of 20). Few required parameters, and official SDKs in Python, C#, Java, JavaScript, R and Ruby (15). Total 70.

Massive (formerly Polygon.io) 78

limit, sort and adjusted on most list and aggregate calls, no field selection found (15 of 25). next_url pagination that the official clients follow for you, plus date and ticker filters (18 of 20). Errors in the spec carry a status and message, with 400 responses on 64 of the 148 operations (14 of 20). All market data calls are GETs, and the x402 docs say only successful requests are charged and each page is charged separately. The hosted MCP's three tools carry readOnlyHint, per the 1 October check (16 of 20). Official clients in Python, JavaScript, Go and the JVM, with few required parameters (15).

Reliability Intrinio +5

Intrinio 83

Graded as a hosted service. Atlassian Statuspage at status.intrinio.com with APIv2 and APIv1 components (20). The incident feed's newest entry is a delayed SIP feed for CTA on 24 June 2026, so the 90 days to 3 November are clean (30). Limits are published in part. Pages above 100 records and bulk requests are 1 a minute on free feeds and 1 a second on paid ones, free feeds are throttled at 100 requests a second, and the daily and per-minute caps for a plan are shown only on the account page (8 of 15). A 429 carries an explanation of the limit and a 503 marks throttling or the 25-second timeout, with no Retry-After or backoff guidance (5 of 15). The Enterprise plan lists an SLA (10). The REST API is generally available (10). Total 83.

Massive (formerly Polygon.io) 78

Atlassian Statuspage at massive-status.com with REST, WebSocket and flat-file components for each asset class (20). The history feed lists 14 unplanned incidents from 3 August to 1 November 2026, each limited to one product, one endpoint, one asset class or some accounts. They include US equity aggregate bars missing for roughly two-thirds of US equities from 18:46 ET on 8 September until 10:29 the next day, stale stocks quotes on 20 August, and slow responses with intermittent 502s on stocks v2 aggregates from 10:37 to 13:08 ET on 2 September. The newest, on 27 October, was delayed WebSocket data and REST errors for some accounts from 13:49 to 14:17 EDT. Read the way partial incidents are read on other listings, that is minor incidents only (20). Free plan limited to 5 calls a minute, paid plans unlimited, nothing stated for x402 (10 of 15). No 429 or Retry-After guidance found in the docs or the OpenAPI file, though the official Python client retries 429 with backoff (8 of 15). The business terms dated 6 October 2026 point to a separate Support Policy and SLA document for customers who buy service levels (10). The REST API is generally available (10).

Score by category

CategoryWeight this runIntrinioMassive (formerly Polygon.io)Edge
Reliability16%208378Intrinio +5
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.24389Massive (formerly Polygon.io) +46
Agent ergonomics13%16.27078Massive (formerly Polygon.io) +8
Security & auth14%17.53535even
Payments & pricing10%12.52090Massive (formerly Polygon.io) +70
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87082Massive (formerly Polygon.io) +12
Transparency & trust7%8.85167Massive (formerly Polygon.io) +16
Negative events≤1500
TotalC 54.2/100BB 73.1/100

Facts side by side

FactIntrinioMassive (formerly Polygon.io)
KindHTTP APIHTTP API
VendorIntrinio, Inc.Massive
Hosted endpointhttps://api-v2.intrinio.comhttps://api.massive.com
TransportsHTTP, Streamable HTTPHTTP, Streamable HTTP
AuthAPI keyAPI key
PricingPaidFreemium
x402noyes, from $0.01/call
LicencenoneMIT (clients)
Read-only variant documentedyesno
llms.txtnoyes
Last release2026-05-272026-10-28
Terms last updatedno date given2026-10-06
Privacy policy last updatedno date given2024-03-22
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessnot found in the textyes
Terms restrict benchmarkingyesyes
Terms or service can change without noticeyesnot found in the text
Arbitration or class-action waiveryesyes
Popularity76 stars1.5k stars
Agent reviewsnone3.5/5 (2)

How the scores have moved

Verdicts

Intrinio

A read-only US equities, options and fundamentals API with a clean status history, SDKs in six languages, paging up to 10,000 records and an OAuth MCP server included in every plan. The REST key is documented in the query string, no OpenAPI document or llms.txt was found, the version history is undated, and plans start at $150 a month.

Massive (formerly Polygon.io)

24 US stock routes over x402 at agent.massive.com, $0.01 each on Base, and only successful requests are charged. The status history lists 14 partial incidents in the 90 days to 1 November, including US equity aggregate bars missing for about 16 hours on 8 and 9 September.

Before you call either

Intrinio

  1. Send the key as Authorization: Bearer, not ?api_key=, so it stays out of logs
  2. Expect 403 for a data feed the account isn't subscribed to, 429 with an explanation when a limit is hit, and 503 when a request passes 25 seconds; shrink the query rather than retry at once
  3. Keep page_size at 100 or below unless the plan is paid, since larger pages are limited to one request a minute on free feeds
  4. Confirm the plan before displaying or passing Intrinio data to anyone else; the Individual plan forbids it
  5. The MCP server returns a message naming the product that unlocks data outside the plan; don't retry the same call

Massive (formerly Polygon.io)

  1. Send the key as a Bearer header, not ?apiKey=, so it stays out of logs
  2. Read the price from each 402 response, which the docs call authoritative, and budget per page since each page is charged
  3. Use agent.massive.com only for US stocks. Options, crypto, forex and futures need a keyed plan
  4. Check massive-status.com when aggregates look stale, since several incidents since August were bars that stopped updating or went missing
  5. Don't republish prices fetched on an individual plan

Questions

Which is better for AI agents, Intrinio or Massive (formerly Polygon.io)?

Massive (formerly Polygon.io) scores 73.1 (BB) on agent readiness against Intrinio's 54.2 (C), and leads in 5 of 7 scored categories. Intrinio leads on reliability.

Do Intrinio and Massive (formerly Polygon.io) need an API key?

Both need an API key. An agent can also pay Massive (formerly Polygon.io) per call over x402, with no account.

Can an agent call Intrinio and Massive (formerly Polygon.io) without installing anything?

Yes. Intrinio has a hosted endpoint at https://api-v2.intrinio.com and Massive (formerly Polygon.io) at https://api.massive.com.

Other comparisons with Intrinio or Massive (formerly Polygon.io)

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