Perenmail vs Mailosaur
Both tools help developers check the email their own products send, but they solve the problem from opposite ends. Mailosaur gives you test email and SMS servers plus APIs and SDKs, built primarily for automated testing — you assert on messages programmatically inside a CI pipeline. Perenmail is a polished, human-in-the-loop console for manual inspection, with persistent private inboxes you can open and read like any mailbox.
If you want a self-serve place to see what actually landed — copy an OTP, open a link, read raw headers — without wiring a test harness first, Perenmail is aimed at you. If you want those checks codified and running on every push, that is squarely Mailosaur’s home turf.
How the two compare
| Dimension | Perenmail | Mailosaur |
|---|---|---|
| Primary use | Manual, human-in-the-loop inspection of email your own product sends. | Programmatic assertions on email (and SMS) inside automated test suites. |
| Automation vs manual | Manual: you read, copy and inspect messages in a UI, no test harness needed. | Automation-first: you write code against APIs/SDKs to assert on messages in CI. |
| Inbox persistence | Persistent by default — inboxes stay until you archive or delete them. | Server-based inboxes; message retention and cleanup are configured for test runs. |
| Setup required | Sign up, name an inbox, point your app's mail at it. No API wiring to get value. | Provision a server and integrate the SDK/API into your test code. |
| OTP / link capture in UI | One-tap: verification codes and every link are extracted for you in the console. | Codes and links are read programmatically via the API in your test code. |
| Raw headers & auth results | Full RFC822 view with synthesized SPF, DKIM and DMARC results in the UI (Personal+). | Message metadata and content are available through the API for assertions. |
| Best for | A developer who wants to see what actually arrived, right now, without writing tests. | Teams building automated email/SMS coverage into a CI pipeline. |
Accurate as of 2026. Mailosaur’s product evolves — verify the current specifics on Mailosaur’s own site before you decide.
When Perenmail fits
You are a developer who wants to trigger a signup, password reset or transactional email and immediately read what arrived — no SDK, no CI job, no assertions to write. You value persistent inboxes for delayed and cron email that are still waiting when a digest fires next week, plus one-tap OTP capture and raw header and auth inspection right in the UI.
When Mailosaur is the better fit
You need programmatic assertions running in CI — a test that fails the build when a verification email does not arrive or its contents change — or you want automated coverage that spans both email and SMS. That end-to-end, code-driven testing is what Mailosaur is built for, and it is the right tool when your goal is a repeatable check rather than a human reading the message.
Built for looking, not just asserting
A lot of email debugging is not “did the test pass” — it is “why does this message look wrong.” Rendering differs, a link points at staging, an OTP is missing, DKIM is failing on one path. For that, you want to open the message and look. Perenmail renders HTML bodies in a locked, script-free sandboxed iframe and lets you toggle Rendered, Text and Source, so you can inspect a hostile or malformed message safely.
Because inboxes are persistent by default, the address you used last month is still there with its history intact — useful when you are chasing an intermittent delivery problem rather than a clean single test run. Group inboxes into projects, label them with markers, and search across everything. Pricing is single-developer and starts free; see the full plan breakdown, and the FAQ covers the common questions. Many teams use both: Perenmail for fast manual inspection, an automation API for CI gates.
See what your app actually sends.
Spin up a private, persistent inbox and read the next email your product sends — no API wiring required. Free to start.