# Gmail API vs Zoho Mail API

> Gmail API scores 77.8 (BB) on agent readiness against Zoho Mail API's 53.8 (D), and leads in every scored category. Both do mailbox read. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/gmail-api-vs-zoho-mail
- Markdown: https://www.anchorterminal.com/compare/gmail-api-vs-zoho-mail.md (~2,100 tokens)
- Slim: https://www.anchorterminal.com/compare/gmail-api-vs-zoho-mail.min.md (~680 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/gmail-api-vs-zoho-mail.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-09

Gmail API scores 77.8 (BB) on agent readiness against Zoho Mail API's 53.8 (D), and leads in every scored category. Both do mailbox read.

- Gmail API: grade BB, 77.8/100, rank #18 of 842. Markdown https://www.anchorterminal.com/tools/gmail-api.md · JSON https://www.anchorterminal.com/api/v1/tools/gmail-api.json
- Zoho Mail API: grade D, 53.8/100, rank #626 of 842. Markdown https://www.anchorterminal.com/tools/zoho-mail.md · JSON https://www.anchorterminal.com/api/v1/tools/zoho-mail.json

## Which one, for what

### Gmail API (BB)

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 63
- Schema & documentation, 82 against 45
- Agent ergonomics, 82 against 56
- Security & auth, 81 against 67
- Payments & pricing, 35 against 30
- Maintenance & community, 85 against 33
- Transparency & trust, 82 against 73

Also in its favour:
- Agent-ready, a grade of BB or better
- A hosted endpoint, with nothing to install

Watch for: Eight restricted scopes, including `gmail.readonly` and `gmail.metadata`, need restricted-scope verification for a public app

### Zoho Mail API (D)

Good for: An agent working inside its owner's Zoho Mail mailbox or administering a Zoho Mail organisation, where narrow scopes and the MCP server keep access small.

Also in its favour:
- Free to start without a card

Watch for: The Zoho Mail usage policy, updated 2 September 2026, lists automated, bulk and transactional emails among uses that are not allowed.


## Score by category

| Category | Weight | Gmail API | Zoho Mail API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 90 | 63 | Gmail API +27 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 82 | 45 | Gmail API +37 |
| Agent ergonomics | 13% (16.2 this run) | 82 | 56 | Gmail API +26 |
| Security & auth | 14% (17.5 this run) | 81 | 67 | Gmail API +14 |
| Payments & pricing | 10% (12.5 this run) | 35 | 30 | Gmail API +5 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 85 | 33 | Gmail API +52 |
| Transparency & trust | 7% (8.8 this run) | 82 | 73 | Gmail API +9 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **77.8 · BB** | **53.8 · D** | |

## Facts side by side

| Fact | Gmail API | Zoho Mail API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Google | Zoho |
| Hosted endpoint | `https://gmail.googleapis.com/gmail/v1` | no (local only) |
| Transports | HTTP, Streamable HTTP | HTTP |
| Auth | OAuth | OAuth |
| Pricing | Free | Freemium |
| x402 | no | no |
| Licence | Apache-2.0 (client libraries) | Proprietary service under the Zoho Terms of Service and the Zoho Mail usage policy. No source repository was found |
| Tools exposed | 23 | none |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2026-09-23 | none |
| Terms last updated | 2021-11-09 | 2022-03-02 |
| Privacy policy last updated | 2026-10-01 | 2025-12-22 |
| Customer content may train models | yes | yes |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | not found in the text | yes |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | 12k stars, 1.1M npm/wk | none |

## Verdicts

**Gmail API.** Fourteen OAuth scopes separate labels, sending, metadata and read-only access, and the quota page gives every method a unit cost. Eight of the scopes are restricted, read-only and metadata among them, so a public app that reads mail needs Google's verification and an annual third-party security assessment. Gmail mailboxes only.

**Zoho Mail API.** A REST API over a Zoho Mail mailbox with OAuth scopes that narrow to one resource and one operation, plus an MCP server launched in 2026. Zoho publishes no OpenAPI file, SDK, request rate limit or API changelog, and its usage policy bars automated email.

## Before you call either

### Gmail API

1. Ask for the narrowest scope. `gmail.labels` is non-sensitive and `gmail.send` is sensitive, while every scope that reads mail is restricted
2. List with `messages.list` and `q` in Gmail search syntax, then fetch each ID with `format=metadata` or `full`. List calls return IDs only
3. Send by posting an RFC 2822 message, base64url encoded, in `raw`. Set `threadId` and matching reply headers to stay in a thread
4. Store the `historyId` and call `history.list`. On a 404, run a full sync. Call `watch` again at least every 7 days
5. Back off exponentially on 403 and 429 rate errors, and keep batches to 50 requests or fewer

### Zoho Mail API

1. Send `Authorization: Zoho-oauthtoken <token>`, not `Bearer`. The token response says `Bearer`, but the OAuth guide says the Mail API requires the Zoho prefix.
2. Use the host for the account's data centre, such as `mail.zoho.eu` or `mail.zoho.in`. Call `GET /api/accounts` first for the `accountId` every mailbox call needs.
3. Reading a message body needs both `folderId` and `messageId`. List and search calls return a summary only, 10 messages by default and 200 at most.
4. Request `ZohoMail.messages.READ` alone for a reading agent. Add `CREATE` only when it must send, and leave `DELETE` out unless required.
5. Refresh the access token every hour, and post OAuth parameters in the request body where the server accepts it, to keep secrets out of URLs.

## Questions

### Which is better for AI agents, Gmail API or Zoho Mail API?

Gmail API scores 77.8 (BB) on agent readiness against Zoho Mail API's 53.8 (D), and leads in every scored category.

### Do Gmail API and Zoho Mail API need an API key?

Both use an OAuth sign-in.

### Can an agent call Gmail API and Zoho Mail API without installing anything?

Gmail API has a hosted endpoint at https://gmail.googleapis.com/gmail/v1. No hosted endpoint is listed for Zoho Mail API.


## For agents

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

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