TEXTING SANDBOX

Test SMS integrations in minutes with a free texting sandbox

A texting sandbox lets you simulate the Sinch SMS API end-to-end without sending real messages or paying. Build, debug, and verify your integration safely before going live.

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Join over 190,000 businesses, including 8 of the 10 largest tech companies in the world

WHY SINCH

Build, test, and debug messaging flows without costs or risks

Get instant sandbox credentials, unlimited free test messages, and true API parity so your code works the same way in production. Test messages in the sandbox are simulated and logged and can only be sent to phone numbers you’ve already verified.

Launch tests in minutes

With instant dashboard access and dedicated credentials, you’ll be sending your first test message in under five minutes.

Free to get started

The sandbox is included with every free developer account. You get unlimited messages, so there’s no paywall to get in the way of your experiments.

Mirror production API

Because every endpoint and webhook matches live traffic, code written in the sandbox works without changes when you switch to production.
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ZERO-RISK TESTING

Safely explore every messaging scenario before customers ever see it

Use the texting sandbox to test features, workflows, and edge cases in a secure, isolated environment. All traffic is simulated against verified numbers, which means no more accidental live sends or unexpected costs.

  • Free test credits when you sign up

  • Production-level security

  • Verified-number controls

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SPEED UP DEVELOPMENT

Go from signup to working code in just a few minutes

The self-contained texting sandbox mirrors our production API. The developer dashboard shows real-time logs of every call and response so you can work, debug, and ship faster.

  • Instant API keys on signup

  • Real-time request and response logs

  • Swap credentials to go live

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DEBUG CONFIDENTLY

Simulate failures and successes to improve your workflows

Trigger over 10 delivery statuses and error codes using documented “magic numbers” to be sure your application handles every outcome before it gets to production.

  • Simulate Delivered, Failed, and more

  • Test webhook error handling

  • Confirm retry logic and alerts

COMMON USE CASES

Where the testing sandbox shines

Initial integration & onboarding

Write your first “Hello, World!” SMS and confirm setup without risk, thanks to the free credentials and verified numbers in the texting sandbox.

End-to-end workflow testing

Validate complete journeys like sending a verification code, receiving replies, and processing webhooks—all inside the texting sandbox.

Automated testing in CI/CD

Build sandbox API calls right into your pipeline to catch issues early, so regressions never reach production and releases stay stress-free.

Feature evaluation

Experiment with scheduling, Unicode, and other advanced capabilities before committing to them for your real messages.

WHAT’S INCLUDED

Everything you need for end-to-end SMS testing

Dedicated API credentials

Keep sandbox and production keys separate to avoid accidentally sending messages.

True API parity

Every endpoint, parameter, and webhook matches production for predictable migrations.

Simulated delivery reports (DLRs)

Trigger Delivered, Failed, and other statuses to test callback handling.

Inbound message simulation

Test inbound processing by sending messages to a virtual number.

Interactive debugging

View real-time logs of requests and simulated responses in the dashboard. 


Unlimited free test messages

Try as many times as you need with no usage caps or hidden fees. 


Direct transition to production

Go live by simply swapping sandbox credentials for production ones. 


Secure environment

The sandbox is built with the same security architecture and authentication as production.

Texting sandbox FAQs

A texting sandbox is a safe, simulated environment to build and test the Sinch SMS API end-to-end without sending real messages or incurring costs. Keep a clear distinction between the sandbox (testing) and production (live) environments to avoid confusion.

Yes. Sign up for a free Sinch Build account to get sandbox credentials and start testing at no cost. 

Use the documented “magic numbers” or parameters in your API calls to trigger specific delivery statuses, including Failed DLRs, and make sure your error handling works correctly. 

No. The sandbox API is the same as production. When you’re ready, simply swap your sandbox credentials for production credentials and start sending real traffic. 

Create a free Sinch Build account to access your sandbox dashboard, API key, and secret key. Start making API calls and view simulated responses in real time. 

Yes. You can embed sandbox API calls in your pipeline to automate tests and catch regressions before release. 

The sandbox shares the production security architecture, requiring API key and secret authentication and restricts messages to only verified phone numbers.