# Fastmail API (JMAP) vs Unipile (slim)

> Unipile scores 58.4 (C) on agent readiness against Fastmail API (JMAP)'s 54.1 (C), and leads in 4 of 7 scored categories. Fastmail API (JMAP) leads on security & auth. Both do mailbox read. Category scores, facts, verdicts and agent notes side by side.

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

Unipile scores 58.4 (C) on agent readiness against Fastmail API (JMAP)'s 54.1 (C), and leads in 4 of 7 scored categories. Fastmail API (JMAP) leads on security & auth. Both do mailbox read.

- Fastmail API (JMAP): C 54.1, rank #620 of 842 · https://www.anchorterminal.com/tools/fastmail.min.md
- Unipile: C 58.4, rank #524 of 842 · https://www.anchorterminal.com/tools/unipile.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. Ahead on Security & auth, 60 against 37.
- Unipile, good for A product that needs one API over Gmail, Outlook and IMAP together with LinkedIn or WhatsApp messaging, priced per account. Ahead on Schema & documentation, 77 against 52; Payments & pricing, 40 against 30; Maintenance & community, 59 against 26. Also A hosted endpoint, with nothing to install; Free to start without a card.

| Category | Fastmail API (JMAP) | Unipile |
| --- | --- | --- |
| Reliability (16%) | 54 | 56 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 52 | 77 |
| Agent ergonomics (13%) | 73 | 73 |
| Security & auth (14%) | 60 | 37 |
| Payments & pricing (10%) | 30 | 40 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 26 | 59 |
| Transparency & trust (7%) | 74 | 71 |

| Fact (where they differ) | Fastmail API (JMAP) | Unipile |
| --- | --- | --- |
| Vendor | Fastmail Pty Ltd | UNIPILE SAS |
| Hosted endpoint | no (local only) | `https://developer.unipile.com/mcp?branch=v1.0` |
| Transports | HTTP | HTTP, Streamable HTTP |
| Auth | OAuth or key | API key |
| 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 | Proprietary service under Unipile's terms of use. The v1 Node SDK repository and the unipile-mcp repository carry an MIT licence file |
| Tools exposed | none | 5 |
| llms.txt | no | yes |
| MCP registry | not listed | `com.unipile/unipile-mcp` |
| Last release | 2026-04-22 | 2026-09-02 |
| Privacy policy last updated | no date given | 2026-09-28 |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | not found in the text | yes |
| Popularity | 123 stars | 48 stars, 83k npm/wk |