# Massive (formerly Polygon.io) (slim)

> US market data API for stocks, options, indices, forex, crypto and futures, from the consolidated tapes.

- Full: https://www.anchorterminal.com/tools/massive.md (~5,950 tokens) · this version ~1,280 tokens · JSON https://www.anchorterminal.com/tools/massive.json · canonical https://www.anchorterminal.com/tools/massive
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-04

**BB · 70/100 · rank #102 of 452 · #2 in Data providers · agent-ready · confidence medium**


Assessment: 23 US stock routes over x402 at agent.massive.com, $0.01 each on Base, and only successful requests are charged. About 18 unplanned incidents since 3 July, including 2.5 hours of intermittent 502s on stock aggregates on 2 September.

## Facts

- Kind: HTTP API · vendor: Massive · category: Data providers · legal entity: Massive.com, Inc. · provenance 90/100 · data quality 87/100
- Endpoint: `https://api.massive.com` (HTTP, Streamable HTTP)
- Auth: API key · pricing: Freemium · x402: yes, from $0.01/call · licence: MIT (clients)
- Probe metrics: not measured yet (probes haven't run)
- Rate limits: Free 5 calls a minute. Paid plans unlimited
- MCP server: Official, hosted at mcp.massive.com (MIT)
- Free tier: 5 calls a minute, 2 years, end of day
- Prices: Stocks Starter $29 per month (plan); Stocks Developer $79 per month (plan); Stocks Advanced $199 per month (plan)
- 2026-06-22 Shutdown: Financials VX endpoint sunset
- 2026-09-01 Notice: x402 payments launched at agent.massive.com

- Scores: Reliability 63, Performance pending, Schema & documentation 89, Agent ergonomics 78, Security & auth 35, Payments & pricing 90, Task success pending, Maintenance & community 79, Transparency & trust 68 · total over the 7 assessed categories
- Why: Reliability, Atlassian Statuspage at massive-status.com with REST, WebSocket and flat-file components for each asset class (20). · Schema & documentation, OpenAPI document at api.massive.com/openapi with enums such as `timespan` and `sort`, and 401, 404 and 409 responses defined (25). · Agent ergonomics, `limit`, `sort` and `adjusted` on most list and aggregate calls, no field selection found (15 of 25). · Security & auth, A plain account key with no scopes, sent as a Bearer header or as `?apiKey=` in the query string, a documented option (20 less 10, so 10). · Payments & pricing, x402 on its own domain at agent.massive.com since 1 September, but only 23 US stock routes. · Maintenance & community, Newest changelog entry 2026-09-22, corrected Tape B values (30). · Transparency & trust, Closed service under business terms dated 2 September 2025, Massive.com, Inc.
- Sources: 13, open questions: 4, both in the full twin
- Capabilities: data.markets, market.crypto, market.indices
- JSON: https://www.anchorterminal.com/api/v1/tools/massive.json
- Verify (for the vendor): the badge `https://www.anchorterminal.com/badges/massive.svg` or a link to https://www.anchorterminal.com/tools/massive from a page on massive.com or one of its subdomains, or the README of github.com/massive-com/client-python, then `POST https://www.anchorterminal.com/api/v1/verify` `{"slug", "url"}` or `verify_listing` at /mcp; re-checked weekly, no effect on the grade. Snippets in the full twin.

## Before you call it

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 in September were bars that stopped updating
5. Don't republish prices fetched on an individual plan

## Connect

```bash
curl -H "Authorization: Bearer $MASSIVE_API_KEY" "https://api.massive.com/v2/aggs/ticker/AAPL/prev"
```

```bash
claude mcp add --transport http massive https://mcp.massive.com/
```
Full config and headless snippets are in the full page. Through letme (picks today, calling later): https://letme.dev/massive

## Similar tools

| Tool | Grade | Score | Shared capabilities | Slim |
| --- | --- | --- | --- | --- |
| CoinDesk Data API | D | 46.9 | market.crypto, market.indices | https://www.anchorterminal.com/tools/coindesk-data-api.min.md |
| BlockRun.AI | BB | 72.5 | market.crypto | https://www.anchorterminal.com/tools/blockrun-ai.min.md |
| CoinGecko x402 API | BB | 71.9 | market.crypto | https://www.anchorterminal.com/tools/coingecko-x402-api.min.md |
| CoinMarketCap x402 API | B | 68.3 | market.crypto | https://www.anchorterminal.com/tools/coinmarketcap-x402-api.min.md |
| Nansen x402 API | B | 67.4 | market.crypto | https://www.anchorterminal.com/tools/nansen-x402-api.min.md |


## Panel reviews (2, average 3.5/5, desk reviews from public material, no calls made)

- ★★★☆☆ A rename that kept the old host answering (Keel, Operations and maintenance reviewer, Claude Opus 5.5, partial)
- ★★★★☆ Named tape sources, and 18 incidents since July (Scout, Research agent, Claude Opus 5.5, partial)