Email sending, without the complexity
MailerJson is a South African email API. You send an email with one request, and we handle the rest, the delivery and the record of what happened to it. We built it for developers and businesses who want to send emails to their customer's inbox.
Most email services are priced in dollars, billed monthly and designed around large teams. We wanted the opposite: pricing in rand, no monthly plan, and a way to test properly before a real customer is involved.
That is why credits and the virtual sandbox are at the centre of the product. You pay for the emails you send in production, and everything you send while building is free and stays in the sandbox.
Welcome aboard
Sandboxhello@yourapp.com
Every test email lands in the sandbox. Open it and check it at any size.
- Based in
- South Africa
- Pricing
- R3,50 per 1000 credits
- Testing
- Unlimited sandbox emails
- History
- 30 days of sent emails
Every feature in one box
Pay only for what you send
There is no monthly plan to outgrow or pay for while you are idle. You buy credits, and each email you send in production uses a few of them. Credits are R2,70 per 1000, and the price stays the same however many you buy. Because testing happens in the sandbox, your credits only go on emails that real users receive.
Virtual sandbox for testing
Grab a sandbox key and start sending right away, with no credits needed. Every email you send is intercepted and shown inside the virtual sandbox, so you can open it and see exactly how it looks at desktop, tablet and phone sizes. There is no limit on how many emails you send to the sandbox, so you can test as much as you like until the result is right.
Queued, fast sending
When your app calls the API, the email is accepted and placed in a queue straight away. Delivery then happens in the background, so your request returns quickly and a slow send never blocks a signup or checkout. A burst of traffic on your side gets queued instead of overloading anything.
Unlimited workspaces and templates
Create a workspace for each project, product or client so their emails stay separate and easy to find. Save your layouts once, such as welcome emails, password resets and receipts, and reuse them from any workspace. Your code only needs to send the template and the values that change. There is no cap on either, so growing never changes your bill.
3 months of email history
Every email you send in production is recorded, so when a user says they never got their reset link you can check what happened instead of guessing. History is kept for 30 days, which covers most support questions and debugging sessions. It is included on every account.
Safe switch to production
Going live is a one-line change: replace your sandbox key with a production key. Production keys come from the production dashboard, not the sandbox dashboard, so a test key can never send real email by accident. Keep each key in an environment variable on your server and it never has to reach the browser.
From first test to first customer
- 1
Start in the sandbox
Create an account and grab a sandbox key. No credits to buy, nothing to set up. Send your first email with one API call and it appears in the virtual sandbox within moments.
- 2
Check every email visually
Open any email and see it at desktop, tablet and phone sizes. Nothing reaches a real inbox and there is no limit, so keep testing until it is right.
- 3
Swap in your production key
Take a production key from the production dashboard and use it in place of the sandbox key. Your code stays the same. Top up with Paystack and your emails reach real users.
- 4
Track what was sent
Every production email is recorded with its delivery status for 30 days. When someone says they never got a message, look it up instead of guessing.
Loved by developers
Teams shipping email without friction.
Jane Doe
Backend EngineerSwapped our SMTP setup for a single API call. Delivery got faster and the code got shorter.
John Smith
Indie HackerI took a sandbox key and sent my first test email in under five minutes. Seeing it at phone and desktop size before anything went out saved me from shipping a broken layout.
Noah Williams
CTO, NorthwindWe moved transactional email over in a weekend. Workspaces let each client project keep its own keys and usage, which used to be a spreadsheet job.
Amara Okafor
Founder, Acme LabsBuying credits instead of a monthly plan makes costs predictable, which matters a lot when you are bootstrapping. I always know what a campaign will cost before it goes out.
Liam Chen
Fullstack DeveloperClean API, sensible errors, and the docs have working examples. Going live was just replacing the sandbox key with the production key.
Ethan Brooks
Software EngineerWorks anywhere I can make an HTTP request. PHP, Node and a cron job in bash all use the same API.
Sofia Martins
DevOps EngineerQueued sending means a traffic spike on our side no longer turns into a rate-limit incident. We stopped worrying about retries.
Zanele Dlamini
Student DeveloperFinally an email service that does not feel built for enterprises only. I could test as much as I wanted in the sandbox without spending anything.
Priya Nair
Product EngineerPaying in rand and topping up with Paystack removed a lot of friction for us. The 30-day history has already helped me track down a missing password reset.
We're here to help
Do I need a monthly plan?
No. There are no monthly plans. You buy credits when you need them and each production email uses some of them. Credits cost R2,70 per 1000, and the price stays the same however many you buy.
What is the virtual sandbox?
It is a testing environment where you can send emails with a sandbox key and nothing reaches a real inbox. The emails are intercepted and shown inside the sandbox, where you can open each one and see how it looks at desktop, tablet and phone sizes before any real user sees it.
Do sandbox emails cost credits?
No. The sandbox has no limit, so you can send as many test emails as you like without using any credits. Your credits only go on emails sent in production.
How do I go live when I'm ready?
Replace your sandbox key with a production key. Production keys come from the production dashboard, not the sandbox dashboard. The rest of your code stays the same, and a sandbox key never sends real email.
Which languages and frameworks can I use?
Anything that can make an HTTP request. You send emails with a single API call, so it works the same from JavaScript, PHP, Python, Go or even a cron job written in bash. You can also connect it to tools like WordPress, Supabase and PocketBase.
How many workspaces and templates can I create?
As many as you want. Use a workspace for each project or client so their emails stay separate, and save your layouts as templates to reuse from any workspace. Neither one is capped or changes what you pay.
How long is my email history kept?
Production emails are kept for 30 days. That is enough to check whether a message was sent when a user says they never received it, and to debug problems after a release.
Where should I keep my API key?
In an environment variable on your server, never in code that runs in the browser. Anyone who has your key can send on your behalf. Use the sandbox key while developing and the production key only on your live server.