The reset link that points to localhost
It worked on your laptop. Your customer clicked http://localhost:8000/reset and got nothing.
01
Free for Windows, macOS & Linux · v0.1.2
MailCatch Test every email. Send none.
MailCatch catches every email your app sends, right on your machine, so you see exactly what your users will get. Then it tells you what's wrong with it. Sign-up codes, password resets, invoices, newsletters: preview, check and test them before anyone else does.
- Works with any language or framework
- Nothing reaches a real inbox by accident
- No account needed
- API & CLI for your tests
- Setup time
- < 1 minute
- SMTP port
- 1025
- Price
- $0
- Emails sent to real people
- 0
Email is the part of your app you can't see
Every team has shipped one of these.
During development you either send real emails to real people and hope, or you never look at them at all. MailCatch makes every email visible, checkable and testable before it matters.
"Hi {{ first_name }}"
The welcome email that greeted a thousand new customers with an unfilled template tag.
02The invoice Gmail cut in half
Over 102 KB of HTML and Gmail hides the rest: the total, the footer, the unsubscribe link.
03Perfect in your editor, broken in Outlook
Rounded buttons turn square, layouts collapse, and dark mode makes your logo vanish.
04Set up in under a minute
Three steps. One of them is "use your app".
- 1Install MailCatch and open it
It starts listening straight away. No account, no sign-up, no configuration file.
- 2Point your app at it
Host 127.0.0.1, port 1025, any username and password. That's the whole setup.
- 3Use your app as normal
Every email your app sends appears in MailCatch the moment it's sent.
Ready-made settings built in for
- Laravel
- Symfony
- Rails
- Django
- Node.js
- Python
- PHP
- Go
- Java
- .NET
- curl
# Laravel - or any framework that sends over SMTP
MAIL_MAILER=smtp
MAIL_HOST=127.0.0.1
MAIL_PORT=1025
MAIL_USERNAME=shop-api # picks the inbox
MAIL_PASSWORD=anything
# That's it. Send an email and watch it land.Built for the emails that matter
Everything you wish your inbox did.
Find the code, catch the bug, see every screen size, and know exactly what a template change did.
Sign-up & login testing
The code and the link, one click away.
Testing sign-ups and logins means digging through emails for a six-digit code or a magic link. MailCatch finds them for you, so what used to take a minute of scrolling now takes one click.
- One-time codes detected automatically and shown right in the message list. Click to copy
- Verify, reset and sign-in links get their own button: open it or copy it instantly
- Smart enough to ignore order numbers, prices, dates and phone numbers
Email health checks
Catch the mistakes before your customers do.
Every email gets an instant health check, entirely offline. MailCatch tells you what's wrong, why it matters, and how to fix it.
- Broken templates: unfilled {{ placeholders }}, undefined, NaN and [object Object] in the subject or body
- Links that won't work: localhost, .test domains and private IPs (the classic wrong-base-URL bug), http:// links and buttons that go nowhere
- Gmail clipping: a warning when your HTML passes the 102 KB limit
- Accessibility and deliverability: missing alt text and language, vague "click here" links, no plain-text version, no one-click unsubscribe
- A spam-risk score, and a link checker that runs only when you ask
- Outlook
- Gmail
- Apple Mail
- iOS Mail
- Yahoo Mail
- Outlook.com
- Samsung Email
- Thunderbird
Client support is based on caniemail.com data: see which CSS and HTML features in your email won't work, and where.
Preview
See it the way your users see it.
Your users read email on phones, in dark mode, with images blocked. Now you can too, before you ship.
- Desktop, tablet and mobile widths to catch layouts that don't respond
- Dark mode, two ways: your email's own dark styles (as Apple Mail shows them), and the forced colour inversion of Gmail and Outlook mobile, where logos vanish and text disappears
- Remote images blocked by default, just like real inboxes, with a one-click switch
- Text, headers, raw source and attachments, with inline previews for images, PDFs and text files
Compare
Did that template change break anything?
Pick any two emails and MailCatch shows exactly what changed. Perfect for reviewing a template change before it ships.
- Subject, sender, recipients, size and attachments compared at a glance
- A line-by-line diff of the text and the HTML
- Or both emails rendered side by side
Subject Welcome to Acme - please verify your email
- From Acme <no-reply@acme.test>
+ From Acme App <no-reply@acme.test>
Size 3.0 KB → 3.1 KB
- <h1>Hi {{ first_name }},</h1>
+ <h1>Welcome aboard, Ada</h1>
<p>Thanks for signing up.</p>
- <a href="http://localhost:8000/verify">
+ <a href="https://acme.com/verify">Built for automated tests
Your end-to-end tests can finally check the email too.
Click "Send me a code", wait for the email, read the code, type it in. Three lines, in the
language you already test with, and no flaky sleep(5).
- HTTP API: List, search and fetch messages, read codes and links, clear inboxes.
- /wait: Waits for the email to arrive, so tests are fast and never flaky. No sleep(5).
- Live events: Every new message pushed over WebSocket the moment it lands.
- Headless server: mailcatch serve for CI pipelines and shared development machines.
- JavaScript
- TypeScript
- Python
- PHP
- Go
const mail = new MailCatch();
await page.click("text=Send me a code");
const message = await mail.waitFor({
to: "ada@example.com",
timeout: 30,
});
await page.fill("#code", message.otp_code);$ mailcatch serve # headless, for CI
$ mailcatch wait --to ada@example.com
$ mailcatch tail
$ mailcatch sendChaos mode · Break your email on purpose
Real mail servers time out, reject messages and drop connections. Does your app cope?
Find out on your laptop instead of in production. Turn chaos mode on for one inbox and choose what goes wrong: extra latency, temporary failures, permanent rejections or dropped connections, at exactly the step you want to test. Then watch whether your app retries, and tells the user.
- Latency
- 421
- 451
- 452
- 550
- 552
- 554
- Dropped connection
Everything else you'd expect
Done properly.
-
01
An inbox per project
The SMTP username decides where mail lands, so every app or service keeps its own inbox, with names and colours.
-
02
Instant search
Full-text search across subjects, addresses and bodies, and a list that stays fast with thousands of emails.
-
03
Lives in your tray
Keeps catching mail with the window closed, starts at login, and sends one tidy notification when a test suite sends fifty.
-
04
Release to a real inbox
Need to see it in actual Gmail or Outlook? Forward any email through your own mail server, only to addresses you've allowed.
-
05
Open in your mail client
Read captured mail in Outlook, Thunderbird or Apple Mail over POP3.
-
06
Attachments, previewed
Images, PDFs, text, CSV and JSON open inline. Messages up to 25 MB are accepted by default.
-
07
Automatic cleanup
Keep a set number of messages per inbox, or delete them after a number of days.
-
08
Light, dark & keyboard
Light and dark themes that follow your system, and shortcuts for everything you do often.
Private by design
Your test data stays on your computer.
- Runs entirely on your machineNo account, no cloud, no upload. Test data with real names, addresses and tokens never leaves your computer.
- Never delivers by accidentMailCatch catches mail; it doesn't send it on. Release only works for recipients you've explicitly allowed.
- Safe previewsEmail HTML is shown in a locked-down sandbox with no scripts, and remote content is blocked until you allow it.
- Local by defaultThe SMTP server and API listen only on your own computer unless you choose otherwise, and the API rejects requests from websites.
Works with your stack
If it can send email over SMTP, it works with MailCatch.
On Windows, macOS and Linux. No plugin, no SDK, no code change.
- Laravel
- Symfony
- WordPress
- Ruby on Rails
- Django
- Flask
- FastAPI
- Express
- NestJS
- Next.js
- Spring Boot
- ASP.NET
- Go
- Phoenix
- …and everything else
MailCatch vs testing with a real inbox
Stop guessing what your emails look like.
| Capability | A real inbox | MailCatch |
|---|---|---|
| Where the email goes | A real inbox, maybe a real customer's | Caught on your machine. Never delivered |
| Seeing the email | Log in to a mailbox and wait | Appears the instant it's sent |
| Sign-up codes & magic links | Open, scroll, select, copy | One click, right in the list |
| Broken templates & localhost links | Found by your customers | Flagged on every email |
| Dark mode & mobile | Borrow a phone | Desktop, tablet, mobile, two dark modes |
| Outlook & Gmail support | Guesswork | Feature by feature, per client |
| Automated tests | Polling a mailbox, sleep(5) | HTTP API, /wait, client libraries, CLI |
| Mail server failures | Wait for production | Chaos mode, on demand |
| Your test data | Stored on someone else's servers | Never leaves your computer |
| Price | Often per seat or per message | Free |
Get MailCatch 0.1.2 · Free
Catching mail in a minute.
Pick the file for your system. We'll email you a one-time code (we test our emails too), and the download starts as soon as you enter it.
Windows
Windows 10 and 11, 64-bit
First launch & updates
Windows
If Windows shows "Windows protected your PC", choose More info → Run anyway. On Windows 10, the installer adds Microsoft's WebView2 if it's missing.
Updating
Download the newest version and install it over the old one. Your inboxes, captured emails and settings are kept.
The first-launch warning appears because MailCatch is new and not yet widely downloaded; it only shows once. Verify your download (optional): each file's SHA-256 checksum is in SHA256SUMS.txt.
FAQ
Questions, answered.
Something else? Ideas or partnership enquiries? Email jamal@unravelers.tech.
Is MailCatch really free?
Yes. Download it and use it for as many projects as you like.
Will my emails reach real people?
No. MailCatch catches every email and keeps it on your machine. The only way an email leaves is if you use Release and send it to an address you've added to your allow list.
Do I need to change my code?
No. Change your SMTP host and port to MailCatch's (usually 127.0.0.1 and 1025) in your development settings, the same way you'd configure any mail server.
Can I use it in CI?
Yes. Run the mailcatch serve command-line server on the CI machine, then use the HTTP API, the client libraries or mailcatch wait in your tests.
Can my whole team use it?
Each developer runs MailCatch on their own machine. For a shared staging or CI environment, run mailcatch serve on that machine and point the environment's SMTP settings at it.
What about attachments and large emails?
Attachments are captured and previewable (images, PDFs, text, CSV, JSON), and can be opened or saved. Messages up to 25 MB are accepted by default; you can raise the limit.
Where is my data stored?
In a folder on your computer, which you can open from Settings. Old messages can be cleaned up automatically.
Why does Windows or macOS show a warning the first time?
Both systems double-check apps that aren't yet widely downloaded. It only happens on the first launch; the steps are in the download section above.
Which systems are supported?
Windows 10 and 11 (64-bit), macOS 11 or later on Apple silicon and Intel, and 64-bit Linux (Ubuntu, Debian, Fedora, openSUSE and others).
Before your customers see it
See every email your app sends. Fix it before it ships.
MailCatch is free for Windows, macOS and Linux. Set up in under a minute, and never send a broken email again.