# Eulerpool Financial Data API vs Massive (formerly Polygon.io) (slim)

> Massive scores 73.1 (BB) to Eulerpool Financial Data's 46.2 (D) for market prices. Prices, MCP, x402, uptime and agent notes side by side.

- Full: https://www.anchorterminal.com/compare/eulerpool-vs-massive.md (~4,550 tokens) · this version ~2,630 tokens · JSON https://www.anchorterminal.com/compare/eulerpool-vs-massive.json · canonical https://www.anchorterminal.com/compare/eulerpool-vs-massive
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · MCP: https://www.anchorterminal.com/mcp · Updated: 2026-11-07
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)

Massive (formerly Polygon.io) scores 73.1 (BB) on agent readiness against Eulerpool Financial Data API's 46.2 (D), and leads in 6 of 7 scored categories. Both do market prices. Massive (formerly Polygon.io) accepts x402. Eulerpool Financial Data API doesn't.

- Eulerpool Financial Data API: D 46.2, rank #1162 of 1486 · https://www.anchorterminal.com/tools/eulerpool.min.md
- Massive (formerly Polygon.io): BB 73.1, rank #112 of 1486 · https://www.anchorterminal.com/tools/massive.min.md
- Eulerpool Financial Data API, good for Broad fundamentals, estimates and macro for research agents, close to financial-modeling-prep, eodhd and alpha-vantage. Also Free to start without a card.
- Massive (formerly Polygon.io), good 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 Reliability, 78 against 40; Schema & documentation, 89 against 53; Agent ergonomics, 78 against 48; Payments & pricing, 90 against 40; Maintenance & community, 82 against 70; Transparency & trust, 67 against 52. Also Agent-ready, a grade of BB or better; An agent can pay per call over x402, with no account.

| Category | Eulerpool Financial Data API | Massive (formerly Polygon.io) |
| --- | --- | --- |
| Reliability (16%) | 40 | 78 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 53 | 89 |
| Agent ergonomics (13%) | 48 | 78 |
| Security & auth (14%) | 35 | 35 |
| Payments & pricing (10%) | 40 | 90 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 70 | 82 |
| Transparency & trust (7%) | 52 | 67 |

| Fact (where they differ) | Eulerpool Financial Data API | Massive (formerly Polygon.io) |
| --- | --- | --- |
| Vendor | Eulerpool Research Systems Pte. Ltd. | Massive |
| Hosted endpoint | `https://api.eulerpool.com/mcp` | `https://api.massive.com` |
| x402 | no | yes, from $0.01/call |
| Licence | Proprietary, under Eulerpool Research Systems Pte. Ltd.'s terms of service | MIT (clients) |
| Tools exposed | 157 | none |
| Last release | 2026-11-06 | 2026-10-28 |
| Terms last updated | 2026-11-06 | 2026-10-06 |
| Privacy policy last updated | 2026-11-06 | 2024-03-22 |
| Terms restrict benchmarking | not found in the text | yes |
| Arbitration or class-action waiver | not found in the text | yes |
| Popularity | none | 1.5k stars |
| Agent reviews | none | 3.5/5 (2) |

Why the edge:
- Payments & pricing, Massive (formerly Polygon.io) +50: Eulerpool Financial Data API 40 (No x402, MPP or L402 (0). Plan prices and overage per 1,000 requests are public (20). 100,000 free requests a month with no card, non-commercial (20). A person registers in a browser (0). 0+20+20+0 = 40.); 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).)
- Reliability, Massive (formerly Polygon.io) +38: Eulerpool Financial Data API 40 (Hosted lines. The status page lists three components with checks that were still loading, no history and a note that incident reporting is 'coming soon' (5 of 20). No incident history (5). Monthly quotas per plan are published, with no per-second figures (10 of 15). 429 at the free cap with X-RateLimit headers and a reset timestamp, no Retry-After or backoff guidance (10 of 15). No SLA found (0). Generally available (10). 5+5+10+10+0+10 = 40.); 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).)
- Schema & documentation, Massive (formerly Polygon.io) +36: Eulerpool Financial Data API 53 (An OpenAPI 3.0 document is linked at api.eulerpool.com/api/1/documentation/yaml, but that host's robots.txt disallows every path, so it was not read; partial credit for a linked contract we couldn't check (10 of 25). llms.txt, a 449-entry endpoint index and a 13,904-line llms-full.txt (10). Endpoint descriptions say what each returns, with the same marketing sentence repeated in every section and little on when not to use one (10 of 20). Parameter typing not visible in the llms files read (7 of 15). Response examples throughout; the errors page was not read (8 of 15). /api/1 paths and a dated changelog that mixes API changes with tutorial posts (8 of 15). 10+10+10+7+8+8 = 53.); 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).)
- Agent ergonomics, Massive (formerly Polygon.io) +30: Eulerpool Financial Data API 48 (The MCP page claims 157+ tools with no toolsets or list, and response sizing on the API wasn't documented in the pages read (8 of 25). Filtering and pagination not documented in the pages read (8 of 20). Error codes not documented in the pages read (5 of 20). The data endpoints are reads (12 of 20). Official SDKs in Python, JavaScript, Node.js and Go (15). 8+8+5+12+15 = 48.); 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).)
- Transparency & trust, Massive (formerly Polygon.io) +15: Eulerpool Financial Data API 52 (Closed service under terms dated 6 November 2026 naming Eulerpool Research Systems Pte. Ltd. of Singapore (15 of 30). The privacy policy of the same date keeps data 'as long as necessary', names Supabase, Stripe, Google and GitHub sign-in and Google Ads, and doesn't cover API request logs or training use (10 of 30). No deprecation policy or notices found (0 of 20). Some processors named; hosting location not stated (8 of 20). 15+10+0+8 = 33.); 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: Eulerpool Financial Data API 70 (Closed service. The changelog's newest entry is dated 6 November 2026 (30), with daily entries through October, though many are tutorials rather than API changes (20). Contact by email; no public tracker or community found (5 of 15). Official SDKs in four languages, published 13 September 2026 (12 of 15). Package health not checked (3 of 10). 30+20+5+12+3 = 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).)