The Best Temp Mail API, Compared
If you are testing a sign-up flow, the question is narrower than "which temp mail service is best". It is: which API gives you an inbox per test run and hands back the verification code without you parsing MIME.
Your Temporary Email Address
Waiting for mail...
- No signup
- 24-hour inbox
- OTP auto-detect
- Zero tracking
- Android · Chrome · Firefox
- Developer API
What actually matters in a temp mail API
Most comparisons list inbox counts and domains. For test automation only four things decide it:
- An inbox per run. A shared mailbox collides the moment two CI jobs overlap, and the resulting flake looks like a product bug.
- The code extracted server-side. If the API returns raw MIME, you are writing a regex that breaks the next time someone edits the email template.
- A lifetime longer than the test. Ten minutes is tight for a suite that retries.
- Auth that belongs in CI. A first-party key you can rotate, not a marketplace subscription in front of someone else's key.
How the options compare
| Service | OTP extracted | Inbox lifetime | API access |
|---|---|---|---|
| TempMailGrab | Yes, server-side | 24h, extendable to 48h | Free, first-party key |
| Mailinator | No | Short on the free tier | Paid plans |
| MailSlurp | No | Configurable | Paid, generous free tier |
| mail.tm / mail.gw | No | Short | Free, no key required |
| Guerrilla Mail | No | About 1 hour | Free |
| temp-mail.org | No | Short | Via RapidAPI |
The column that separates them is the first one. Every service here will hand you a message; almost none will hand you the code out of it, so that parsing lands in your test suite instead.
Where each one is the right answer
TempMailGrab when you want the code as a field rather than a regex, a window long enough for a retrying suite, and a free first-party key. That is the case this API was built for.
MailSlurp when you need breadth beyond receiving — sending, custom domains, IMAP/SMTP access, larger org features. It is a bigger product with pricing to match, and if you need those things it is the stronger fit.
Mailinator for large team QA on paid plans with private domains, which TempMailGrab does not offer at all. Its free tier is public by design: any inbox is readable by anyone who types the name, which is fine for meaningless test mail and unsuitable for a real verification code.
mail.tm or mail.gw when you want something free with no signup at all and are happy to parse the message yourself.
Guerrilla Mail when you need to send as well as receive, which almost nothing else in this category does.
The shared caveat
Every domain in this table appears on disposable-email blocklists. When you are testing your own sign-up that only matters if you block disposable addresses yourself, in which case allowlist the test domain in your test environment. It matters a great deal if you were planning to use these against a third-party service, which is a different activity and not what any of these APIs are for.
What it looks like
The whole point is that the test reads like the user story:
const inbox = await tmg.createInbox();
await signUp(inbox.address);
const otp = await inbox.waitForOtp();Full endpoints are in the API docs, the testing-specific guide is on the email testing API page, and there are worked examples for Playwright and Cypress.
Last verified: . Competitor features and pricing change — check each service directly before choosing.
Automate inboxes with the API
Prefer to script it? Generate disposable inboxes and read auto-parsed OTPs & verification links programmatically — built for QA, test automation, and bots. The same private inboxes, over a clean REST API.
# 1. Create a private inbox
curl -X POST https://tempmailgrab.com/api/v1/inbox \
-H "Authorization: Bearer $TMG_API_KEY"
# → { "id": "inb_…", "address": "a1b2c3d4e5f6@tempmailgrab.com" }
# 2. Poll for mail — the OTP + verification links are auto-extracted
curl https://tempmailgrab.com/api/v1/inbox/$ID/messages \
-H "Authorization: Bearer $TMG_API_KEY"
# → { "messages": [{ "extracted_otp": "123456", "extracted_links": [ … ] }] }Related guides
Frequently Asked Questions
What is the best temp mail API for testing?
It depends on what you need beyond receiving. For getting a verification code into a test without parsing MIME, an API that extracts the code server-side is the one that saves you work. For sending, custom domains or IMAP access, a broader product like MailSlurp fits better. For large team QA with private domains, Mailinator paid plans.
Is there a free temporary email API?
Yes. TempMailGrab offers a free first-party key with OTP extraction included, and mail.tm and mail.gw are free with no key at all, though you parse messages yourself. Mailinator and MailSlurp put API access behind paid plans, with MailSlurp offering a free tier.
Why does server-side OTP extraction matter?
Without it the code parsing lives in your test suite, which means a regex that breaks whenever someone edits the email template — and it breaks as a failing test that looks like a product bug. Extracting server-side means the code arrives as a field regardless of whether the sender put it in the subject, the text body or only the HTML.
Will a disposable address work against any signup?
No. Every disposable domain appears on blocklists that many services check. When testing your own signup that is only an issue if you block such addresses yourself, in which case allowlist the domain in your test environment.