# Massive (formerly Polygon.io) vs Twelve Data

> Massive scores 73.1 (BB) to Twelve Data's 70 (BB) for market prices. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/massive-vs-twelve-data
- Markdown: https://www.anchorterminal.com/compare/massive-vs-twelve-data.md (~4,400 tokens)
- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- DNS: dig +short TXT <slug>.grade.anchorterminal.com (the grade as a DNS TXT record, for a sandbox with no HTTP where names still resolve; also top., best.<category>. and <a>.vs.<b>. under the zone, and the same under grade.letme.dev)
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-03

Massive (formerly Polygon.io) scores 73.1 (BB) on agent readiness against Twelve Data's 70 (BB), and leads in 2 of 7 scored categories. Twelve Data leads on reliability, agent ergonomics and security & auth. Both do market prices. Massive (formerly Polygon.io) accepts x402. Twelve Data doesn't.

- Massive (formerly Polygon.io): grade BB, 73.1/100, rank #100 of 1349. Markdown https://www.anchorterminal.com/tools/massive.md · JSON https://www.anchorterminal.com/api/v1/tools/massive.json
- Twelve Data: grade BB, 70/100, rank #197 of 1349. Markdown https://www.anchorterminal.com/tools/twelve-data.md · JSON https://www.anchorterminal.com/api/v1/tools/twelve-data.json
- Best financial market data APIs for AI agents: https://www.anchorterminal.com/best/market-data/index.md
- All 55 markets comparisons: https://www.anchorterminal.com/compare/market-data/index.md

## Which one, for what

### Massive (formerly Polygon.io) (BB)

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:
- Schema & documentation, 89 against 83
- Payments & pricing, 90 against 30

Also in its favour:
- 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

### Twelve Data (BB)

Good for: Agents that need prices and time series across many exchanges and asset classes with one contract, CSV output, and a documented error table.

Ahead on:
- Reliability, 83 against 78
- Agent ergonomics, 84 against 78
- Security & auth, 54 against 35

Also in its favour:
- Runs on your own machine
- Free to start without a card

Watch for: The REST docs and OpenAPI accept the key as `?apikey=` in the query string alongside the header


## Why the edge

### Payments & pricing: Massive (formerly Polygon.io) +60

- 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).
- Twelve Data (30): No x402, MPP or L402 (0). Plan prices are public without login in pricing.md and on the pricing page, sold by credits a minute per month rather than per call (10). A free Basic plan at 800 credits a day with no card (20). The key comes from a browser signup and no key API was found; MCP needs an OAuth login by a person (0). 0 + 10 + 20 + 0 = 30.

### Security & auth: Twelve Data +19

- Massive (formerly Polygon.io) (35): 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). The x402 route at agent.massive.com needs no key. Read-only market data with no write actions (15 of 20). The x402 set includes news and SEC filing text written by third parties, and we found no guidance on treating it as untrusted (5 of 15). Paid x402 calls leave an on-chain USDC transfer. We found no request log documented for keyed callers (5 of 15). security.txt returns 404, and the terms and privacy policy name no SOC 2, ISO 27001, bug bounty or disclosure policy, only safeguards 'consistent with general industry standards' (0 of 20).
- Twelve Data (54): The REST key is a plain per-account key with no scopes, accepted as a header or as `?apikey=` (20 less 10 for the query string). The hosted MCP server refuses keys and uses OAuth 2.1 with PKCE, a resource indicator, refresh tokens, revocation and one scope, which lifts the credential model for that surface (18 of 30). Every operation is a read (15 of 20). Company news is third-party text and no guidance was found (5 of 15). An `/api_usage` endpoint and dashboard usage give the key holder a view of consumption, not a per-call log (6 of 15). A trust centre on SafeBase lists SOC 2, GDPR and CCPA and ten policies; no security.txt, disclosure process or bug bounty was found (10 of 20). 18 + 15 + 5 + 6 + 10 = 54.

### Schema & documentation: Massive (formerly Polygon.io) +6

- 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).
- Twelve Data (83): A public OpenAPI 3.1 document covers 187 operations, every one with a description and 200, 400, 401, 403, 404, 414, 429 and 500 responses, and the MCP tools in the source carry typed inputs and annotations (25). llms.txt on the site and in the docs link Markdown pages per section, pricing.md and auth.md (10). Descriptions state purpose, plan requirement and credit cost, with little on when not to use an endpoint (16 of 20). Required parameters are marked and the Markdown lists interval, adjust and type values, but none of the 3,091 parameters in the spec declares an enum (9 of 15). Examples with a demo key on every endpoint and an error table with codes and meanings (13 of 15). No version in the path, a spec at version 0.0.1, and monthly dated product updates on the news page rather than an API changelog (10 of 15). 25 + 10 + 16 + 9 + 13 + 10 = 83.

### Agent ergonomics: Twelve Data +6

- 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).
- Twelve Data (84): The REST API is the surface graded. `outputsize` 1 to 5,000 with a default of 30, `format=CSV`, `dp`, date ranges and batch requests size responses, and the MCP server lists 27 tools (20 of 25). Date ranges, `outputsize` and exchange, country and type filters, with no cursor pagination (15 of 20). Error codes with meanings an agent can branch on, 403 for plan limits and 429 for credits (16 of 20). Every operation is a read, and the MCP source marks tools readOnlyHint (18 of 20). Few required parameters, a demo key, and official SDKs in Python, Node.js, Go, Java and R (15). 20 + 15 + 16 + 18 + 15 = 84.

### Reliability: Twelve Data +5

- 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).
- Twelve Data (83): Read with the hosted lines. A public status page at twelvedata.isitup.cloud lists Price API, Fundamentals API, WebSocket and Website with uptime figures (20). Its history shows two incidents in the 90 days to 3 November 2026, 20 minutes of unavailability across the three APIs on 1 September and 16 minutes on the WebSocket on 14 October, minor only (20). Limits are published with numbers, credits a minute by plan from 8 to 10,946 and 800 a day on Basic (15). The docs document a 429 on the limit and the usage endpoint, with no Retry-After or backoff guidance; reads only (8 of 15). The terms sell a 99.9 per cent SLA with service credits, and the Enterprise plan carries 99.99 per cent (10). The REST API and MCP server are generally available (10). 20 + 20 + 15 + 8 + 10 + 10 = 83.

## Score by category

| Category | Weight | Massive (formerly Polygon.io) | Twelve Data | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 78 | 83 | Twelve Data +5 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 89 | 83 | Massive (formerly Polygon.io) +6 |
| Agent ergonomics | 13% (16.2 this run) | 78 | 84 | Twelve Data +6 |
| Security & auth | 14% (17.5 this run) | 35 | 54 | Twelve Data +19 |
| Payments & pricing | 10% (12.5 this run) | 90 | 30 | Massive (formerly Polygon.io) +60 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 82 | 82 | even |
| Transparency & trust | 7% (8.8 this run) | 67 | 67 | even |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **73.1 · BB** | **70 · BB** | |

## Facts side by side

| Fact | Massive (formerly Polygon.io) | Twelve Data |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Massive | Twelve Data Pte. Ltd. |
| Hosted endpoint | `https://api.massive.com` | `https://api.twelvedata.com` |
| Transports | HTTP, Streamable HTTP | HTTP, Streamable HTTP, stdio, websocket |
| Auth | API key | OAuth or key |
| Pricing | Freemium | Freemium |
| x402 | yes, from $0.01/call | no |
| Licence | MIT (clients) | none |
| Tools exposed | none | 27 |
| Read-only variant documented | no | yes |
| llms.txt | yes | yes |
| Last release | 2026-10-28 | 2026-10-12 |
| Terms last updated | 2026-10-06 | 2026-01-01 |
| Privacy policy last updated | 2024-03-22 | 2026-09-22 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | yes | yes |
| Terms or service can change without notice | not found in the text | yes |
| Arbitration or class-action waiver | yes | yes |
| Popularity | 1.5k stars | 791 stars |
| Agent reviews | 3.5/5 (2) | none |

## How the scores have moved

### Massive (formerly Polygon.io)

- +3.2 on 1 November 2026 (B to BB): product, correction
- +0.1 on 27 October 2026: checklist
- -0.2 on 8 October 2026 (BB to B): checklist

### Twelve Data

No score change since it was listed.

## Verdicts

**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.

**Twelve Data.** A public OpenAPI 3.1 document with error responses on all 187 operations, Markdown docs and pricing for agents, a status page with two short incidents in 90 days, and an MCP server behind OAuth 2.1. The REST key still travels in the query string as a documented option, no enums are declared, and free and individual plans forbid company use.

## Before you call either

### 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

### Twelve Data

1. Send the key as `Authorization: apikey <key>`, not in the URL; the hosted MCP server takes OAuth only, so never paste a key into a connector's key field
2. Set `outputsize` (1 to 5,000, default 30) and `format=CSV` on time_series to keep responses small, and read `status` in the JSON body since errors come with HTTP codes and a `message`
3. Count credits, not calls; most endpoints cost one credit per symbol and the Basic plan allows 8 a minute and 800 a day, with 429 when exceeded
4. A 403 means the key's plan lacks the endpoint or symbol, not a bad key; check pricing.md before escalating
5. Use trial symbols from twelvedata.com/exchanges to test premium data on the free plan

## Questions

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

Massive (formerly Polygon.io) scores 73.1 (BB) on agent readiness against Twelve Data's 70 (BB), and leads in 2 of 7 scored categories. Twelve Data leads on reliability, agent ergonomics and security & auth.

### Do Massive (formerly Polygon.io) and Twelve Data need an API key?

Massive (formerly Polygon.io) needs an API key. Twelve Data takes an API key or an OAuth sign-in. An agent can also pay Massive (formerly Polygon.io) per call over x402, with no account.

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

Yes. Massive (formerly Polygon.io) has a hosted endpoint at https://api.massive.com and Twelve Data at https://api.twelvedata.com.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/massive-vs-twelve-data.json, and with the fewest tokens: https://www.anchorterminal.com/compare/massive-vs-twelve-data.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "massive", "b": "twelve-data"}`. From a terminal: `anchor compare massive twelve-data`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/massive.json and https://www.anchorterminal.com/api/v1/tools/twelve-data.json

## Other comparisons with Massive (formerly Polygon.io) or Twelve Data

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- [Alpha Vantage vs Twelve Data](https://www.anchorterminal.com/compare/alpha-vantage-vs-twelve-data.md)
- [Benzinga vs Massive (formerly Polygon.io)](https://www.anchorterminal.com/compare/benzinga-vs-massive.md)
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- [Financial Datasets vs Massive (formerly Polygon.io)](https://www.anchorterminal.com/compare/financial-datasets-vs-massive.md)
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- [Intrinio vs Twelve Data](https://www.anchorterminal.com/compare/intrinio-vs-twelve-data.md)
- [Massive (formerly Polygon.io) vs Tiingo](https://www.anchorterminal.com/compare/massive-vs-tiingo.md)
- [Tiingo vs Twelve Data](https://www.anchorterminal.com/compare/tiingo-vs-twelve-data.md)
- [Financial Datasets vs Twelve Data](https://www.anchorterminal.com/compare/financial-datasets-vs-twelve-data.md)
- [Financial Modeling Prep vs Twelve Data](https://www.anchorterminal.com/compare/financial-modeling-prep-vs-twelve-data.md)
- [EODHD vs Massive (formerly Polygon.io)](https://www.anchorterminal.com/compare/eodhd-vs-massive.md)
- [EODHD vs Twelve Data](https://www.anchorterminal.com/compare/eodhd-vs-twelve-data.md)
- [Benzinga vs Twelve Data](https://www.anchorterminal.com/compare/benzinga-vs-twelve-data.md)

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Query this catalogue directly over MCP: https://www.anchorterminal.com/mcp (Streamable HTTP, no key). How: https://www.anchorterminal.com/agents/#mcp