# Fastmail API (JMAP) vs Nylas Email API (slim)

> Nylas Email API scores 78.7 (A) 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-nylas-email.md (~2,200 tokens) · this version ~780 tokens · JSON https://www.anchorterminal.com/compare/fastmail-vs-nylas-email.json · canonical https://www.anchorterminal.com/compare/fastmail-vs-nylas-email
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-09

Nylas Email API scores 78.7 (A) 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
- Nylas Email API: A 78.7, rank #13 of 842 · https://www.anchorterminal.com/tools/nylas-email.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.
- Nylas Email API, good for Products that act in their users' own mailboxes across several providers and want one schema, webhooks and OAuth handled. Ahead on Reliability, 77 against 54; Schema & documentation, 93 against 52; Agent ergonomics, 81 against 73; Security & auth, 87 against 60; Payments & pricing, 40 against 30; Maintenance & community, 88 against 26; Transparency & trust, 81 against 74. Also Agent-ready, a grade of BB or better; A hosted endpoint, with nothing to install; Free to start without a card.

| Category | Fastmail API (JMAP) | Nylas Email API |
| --- | --- | --- |
| Reliability (16%) | 54 | 77 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 52 | 93 |
| Agent ergonomics (13%) | 73 | 81 |
| Security & auth (14%) | 60 | 87 |
| Payments & pricing (10%) | 30 | 40 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 26 | 88 |
| Transparency & trust (7%) | 74 | 81 |

| Fact (where they differ) | Fastmail API (JMAP) | Nylas Email API |
| --- | --- | --- |
| Vendor | Fastmail Pty Ltd | Nylas |
| Hosted endpoint | no (local only) | `https://api.us.nylas.com/v3` |
| Transports | HTTP | HTTP, Streamable HTTP |
| Pricing | Paid | Freemium |
| 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 Nylas's terms. The SDKs are MIT |
| Tools exposed | none | 38 |
| Read-only variant documented | yes | no |
| llms.txt | no | yes |
| Last release | 2026-04-22 | 2026-10-07 |
| Terms last updated | no date given | 2025-06-23 |
| Privacy policy last updated | no date given | 2026-01-06 |
| Terms restrict automated access | not found in the text | yes |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | not found in the text | yes |
| Arbitration or class-action waiver | not found in the text | yes |
| Popularity | 123 stars | 181 stars, 289k npm/wk, 90k PyPI/wk |