I built a disposable email API after getting frustrated with every existing option
Hey IH 👋
For the past few months I've been building FreeCustom.email — starting as a
simple temp mail app, and recently shipping a full developer API on top of it.
The problem I kept hitting: I needed disposable inboxes in automated test
suites. Register a user → receive verification email → extract OTP → continue.
Simple flow, but surprisingly painful to automate with existing tools.
MailSlurp works but gets expensive fast. Mailinator's public inboxes are a
security nightmare for anything sensitive. Most others don't even have an API,
or the API is an afterthought bolted onto a consumer product.
So I built what I wanted to use.
What I shipped:
- REST API — register inboxes, list messages, fetch by ID, delete
- OTP endpoint — GET /otp returns the parsed code from the latest email,
no regex required on your end
- WebSocket — real-time push when email arrives, no polling
- Attachments, custom domain inboxes on higher tiers
- Credits system — non-expiring top-up requests so you're never left
stranded mid-month
The free tier is genuinely free — 5k req/mo, no credit card, no trial period.
Current status: paying customers, listed on RapidAPI, submitting to
public-apis this week. Working on Make/Zapier integrations next since
a lot of no-code automation use cases map perfectly to what the API does
(receive OTP → use in next step of automation).
Would love feedback from anyone who's built something similar or has
used disposable email APIs in their own projects. What was missing?
What would make you switch from whatever you're using now?
Playground if you want to try it live:
