# Fastmail API (JMAP) vs Gmail API (slim)

> Gmail API scores 77.8 (BB) on agent readiness against Fastmail API (JMAP)'s 54.1 (C), and leads in every scored category. Both do mailbox read. Category scores, facts, verdicts and agent notes side by side.

- Full: https://www.anchorterminal.com/compare/fastmail-vs-gmail-api.md (~2,200 tokens) · this version ~730 tokens · JSON https://www.anchorterminal.com/compare/fastmail-vs-gmail-api.json · canonical https://www.anchorterminal.com/compare/fastmail-vs-gmail-api
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-09

Gmail API scores 77.8 (BB) on agent readiness against Fastmail API (JMAP)'s 54.1 (C), and leads in every scored category. Both do mailbox read.

- Fastmail API (JMAP): C 54.1, rank #620 of 842 · https://www.anchorterminal.com/tools/fastmail.min.md
- Gmail API: BB 77.8, rank #18 of 842 · https://www.anchorterminal.com/tools/gmail-api.min.md
- Fastmail API (JMAP), good for An agent working in its owner's own Fastmail mailbox, where JMAP gives batched reads, structured search and state-based sync on an open standard, and MCP gives a ready connection with read, write and send levels.
- Gmail API, good for An agent working in a Gmail or Google Workspace user's own mailbox, with search, threads, drafts, labels and incremental sync at no per-account fee. Ahead on Reliability, 90 against 54; Schema & documentation, 82 against 52; Agent ergonomics, 82 against 73; Security & auth, 81 against 60; Payments & pricing, 35 against 30; Maintenance & community, 85 against 26; Transparency & trust, 82 against 74. Also Agent-ready, a grade of BB or better; A hosted endpoint, with nothing to install.

| Category | Fastmail API (JMAP) | Gmail API |
| --- | --- | --- |
| Reliability (16%) | 54 | 90 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 52 | 82 |
| Agent ergonomics (13%) | 73 | 82 |
| Security & auth (14%) | 60 | 81 |
| Payments & pricing (10%) | 30 | 35 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 26 | 85 |
| Transparency & trust (7%) | 74 | 82 |

| Fact (where they differ) | Fastmail API (JMAP) | Gmail API |
| --- | --- | --- |
| Vendor | Fastmail Pty Ltd | Google |
| Hosted endpoint | no (local only) | `https://gmail.googleapis.com/gmail/v1` |
| Transports | HTTP | HTTP, Streamable HTTP |
| Auth | OAuth or key | OAuth |
| Pricing | Paid | Free |
| Licence | Proprietary service under Fastmail's API Terms of Service and API Developer Policy. JMAP is an open IETF standard, and the sample code on GitHub is MIT | Apache-2.0 (client libraries) |
| Tools exposed | none | 23 |
| Read-only variant documented | yes | no |
| Last release | 2026-04-22 | 2026-09-23 |
| Terms last updated | no date given | 2021-11-09 |
| Privacy policy last updated | no date given | 2026-10-01 |
| Customer content may train models | not found in the text | yes |
| Terms restrict automated access | not found in the text | yes |
| Terms restrict benchmarking | yes | not found in the text |
| Popularity | 123 stars | 12k stars, 1.1M npm/wk |