vs MailosaurEmail testing5 min read

Mailosaur vs Mails.ai — catching test emails in Playwright, Cypress and Claude Code

Both tools do the same job in a test suite: give the test an email address, catch the email your app sends to it, and hand back the code or link inside. Mailosaur has done this for years and does more around it. Mails.ai is newer, starts free, and takes much more test mail for the same $20.

What both do

A test signs up with an address it controls, waits for the verification email, reads the code or the magic link, and finishes the flow. Mailosaur returns codes in text.codes; Mails.ai returns codes and links on every received message. Both have a Cypress plugin and a Playwright guide, and Mails.ai also has a Playwright fixture. Both give you unlimited addresses: Mailosaur on one inbox, Mails.ai as plus addresses such as qa.acme+run-1842@in.mails.ai, so each test reads only its own mail.

Where Mails.ai is different

A free plan. Free is $0 with 3,000 inbound replies a month and 20 new plus addresses a day, with no card. Mailosaur has no free plan; it offers a 14-day trial.
More test mail for $20. Pro is $20 a month for 50,000 inbound replies and 1,000 new plus addresses a day. Mailosaur’s entry plan is from $20 a month billed yearly ($25 monthly) for 15,000 inbound emails, at up to 500 a day.
Built for coding agents. The MCP server and Claude Code plugin let Claude Code, Cursor and other agents create a plus address, wait for the email and read the code while they test your app. Mailosaur’s docs list no MCP server (checked October 2026).
One call that waits. received.wait blocks for up to 50 seconds and returns the first message that matches its address, sender and whether it has a code or a link. A CI run that passes the Free plan’s daily limit gets 402 plan_limit_exceeded at once instead of a time-out.

Where Mailosaur leads

SMS testing. Mailosaur gives you phone numbers that receive SMS codes. Mails.ai catches email only.
Email previews. Mailosaur renders your emails across mail clients. Mails.ai does not.
Languages and frameworks. Mailosaur has libraries for Node.js, Java, Ruby, Python, .NET, PHP, Go, Swift and Dart, and guides for Selenium, Cucumber, Robot Framework and WebdriverIO. Mails.ai has TypeScript and Python SDKs, a CLI and a REST API that any language can call.
Track record and team features. Mailosaur is established, with SSO and SCIM for larger teams. Mails.ai is live and self-serve with a small, early customer base.

Which to choose

Choose Mailosaur if your tests read SMS codes, you need email previews, or your suite is in Java, .NET, Ruby, PHP, Go, Swift or Dart and you want a native library.
Choose Mails.ai if your tests only need email codes and links, you want to start free, your CI sends more mail than 15,000 a month or 500 a day, or a coding agent runs your tests.

Switching

Swap the Mailosaur server ID for a Mails.ai agent, give each test a plus address, and replace the message search with received.wait. The email-testing guide shows the Playwright and Cypress versions side by side with the Mailosaur calls they replace.

Side-by-side

Mailosaur vs Mails.ai — feature matrix

Dimension	Mails.ai	Mailosaur
Free plan	✓$0: 3,000 emails and 3,000 inbound replies a month, 20 new plus addresses a day	—No free plan; a 14-day free trial
Entry paid plan	Pro: $20 a month, or $200 a year	From $20 a month billed yearly, or $25 billed monthly
Inbound email on the entry plan	✓50,000 a month	From 15,000 a month, with a daily limit of 500
Test addresses	✓A plus address per test; 1,000 new ones a day on Pro	✓1 inbox with unlimited email addresses
Sign-up codes and magic links	✓`codes` and `links` on every received message	✓`text.codes` and links on every message
Waiting for the email	✓One call that waits up to 50 seconds, filtered by `to`, sender and code or link	✓Its SDKs search for and wait on a matching message
Cypress and Playwright	✓`@mailsai/cypress` plugin and `@mailsai/playwright` fixture	✓cypress-mailosaur plugin and a Playwright guide
SDK languages	TypeScript and Python, plus a CLI and REST	✓Nine: Node.js, Java, Ruby, Python, .NET, PHP, Go, Swift and Dart
MCP server for Claude Code, Cursor and other agents	✓Hosted and npm MCP server with a wait tool, and a Claude Code plugin	—None listed in its docs (checked October 2026)
SMS testing	—Not offered	✓Phone numbers for SMS codes
Email previews across mail clients	—Not offered	✓Email Previews
Track record	—Live and self-serve; small, early customer base	✓Established; its npm package is downloaded about 2.3 million times a month

FAQ

Questions readers ask after this page

Can Mails.ai replace Mailosaur in my Playwright or Cypress tests?

For email codes and links, usually yes. Give each test its own plus address, wait for the email sent to it, and read message.codes or message.links. The email-testing guide at /docs/email-testing has a Coming from Mailosaur section that maps the calls. It is not a replacement if your tests also read SMS codes or need email previews: Mailosaur does both and Mails.ai does neither.

How much test mail does each plan take?

Free takes 3,000 inbound replies a month and mail at 20 new plus addresses a day. Pro is $20 a month for 50,000 inbound replies and 1,000 new plus addresses a day; Scale is $99 a month for 500,000 and 10,000. An address that already received mail that day keeps receiving it, so a test’s second email always arrives. Mailosaur’s entry plan, from $20 a month billed yearly, takes 15,000 inbound emails a month at up to 500 a day.

What happens when a Free workspace passes 20 plus addresses in a day?

Mail to a new plus address is kept only as a record, and a wait for that address answers 402 plan_limit_exceeded at once, with a link to upgrade, so a CI run fails fast instead of timing out.

Can Claude Code catch the code while it tests my app?

Yes. Add the Mails.ai MCP server (hosted, or from npm) or install the Claude Code plugin; the agent asks for a plus address, fills in your sign-up form, then calls the wait tool for the email sent to that address and reads the code. See /docs/mcp and /docs/agent-skills.

Will codes from Google, Apple or my bank arrive?

No. A sign-in code or a verify, sign-in or password-reset link from a service such as Google, Microsoft’s account team, Apple, a payment app or a bank never reaches a plus address; only a record is kept. Mail from your own app arrives, including the codes Azure AD B2C sends for it.

Catch your first test email

Free covers 3,000 inbound emails a month and 20 new test addresses a day, with no card. Upgrade when your suite outgrows it.

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