Comparisons / Mailosaur alternative
A Mailosaur alternative with a free tier
Mailosaur is a mature email and SMS testing platform. If you need SMS, previews of your emails in real clients, or ISO 27001 for a procurement form, it is the stronger tool and this page will not pretend otherwise.
If what you need is an inbox per end-to-end test that waits for the email and hands you the code, both do that job. The differences are the free tier and where the custom domain sits in the price list.
Side by side
| Mailosaur | inboxsink | |
|---|---|---|
| Free use | 14-day trial, no free plan | 1,000 API calls a month, no card, no time limit |
| First paid plan | Personal: $25 a month, or $20 a month billed yearly. 1 inbox, from 15,000 received emails a month | Developer: 29 € a month. 10,000 API calls, 1 custom domain, webhooks |
| Waits for the email | Yes (the Cypress command waits automatically) | Yes: one HTTP route held open up to 120 s, from any language |
| Codes and links extracted | Yes (codes and links on the message) | Yes (otp and link). Digit codes only; a link needs a keyword in its URL |
| Custom domain | Enterprise plan | Included in Developer (one), verified by DNS |
| SMS testing | Add-on, from $37.50 a month | No |
| Client libraries | Node.js, Java, Ruby, Python, .NET, PHP, Go | JavaScript; plain HTTP for the rest |
| Certification | ISO 27001 | None |
The units differ: Mailosaur counts received emails, inboxsink counts API calls. A typical test here makes three calls (create, wait, delete).
Where Mailosaur is the better pick
- You test SMS codes as well as emails.
- You want to see how an email renders in Outlook or Gmail before it ships (their email previews add-on).
- Your team works in Java, .NET or PHP and wants an official client rather than a few lines of HTTP.
- A security questionnaire asks for ISO 27001, SSO or SCIM.
Where inboxsink fits
- You want to wire the tests in and leave them running without a trial clock: the free tier has no end date.
- Your signup form refuses shared test domains, and you need your own domain without an Enterprise contract.
- You want the wait to be one HTTP call, so the same pattern works in Playwright, Cypress, Selenium or a shell script.
What that looks like in practice, run against the real service: Playwright, Cypress, Selenium with Python.
Sources
Read on 13 September 2026. Prices change; check the vendor's page before deciding.
- Plans, prices, add-ons, SSO/SCIM: mailosaur.com/pricing
- Code extraction: docs/automation/codes
- Waiting and link extraction in Cypress: docs/email-testing/cypress
- Custom domains on Enterprise: docs/managing-your-account/managing-domains
- Client libraries: docs/email-testing — ISO 27001: faqs
- inboxsink: pricing and API reference
1,000 calls a month, no card asked. Enough to wire it into your test suite and see if it holds.
Then, when your tests start getting refused: a domain of your own is published nowhere, so it lands on no blocklist — 29 € a month.
Other comparisons
- A Mailinator alternative with private inboxes that wait
Mailinator's public inboxes are readable by anyone. inboxsink gives each test a private inbox that waits for the email and returns the code. Checked 13 Sep 2026.
- A smaller MailSlurp alternative for email tests
MailSlurp vs inboxsink for email tests, prices checked 13 Sep 2026: the free tiers, where MailSlurp does more (SMS, 25+ SDKs), and what a custom domain costs.