The SMS testing tool your staging environment was missing
Test every SMS your app sends — without a real carrier, real credits, or real recipients. Zunoy SMS Inbox is a mock SMS gateway for development and staging. Replace your real provider with our SMS sandbox endpoint. Every message lands here — inspectable, organised, and free.
Works with Twilio · MSG91 · AWS SNS · Exotel · Fast2SMS · Vonage · Textlocal · Any REST gateway
WHAT IS SMS INBOX
A mock SMS gateway that behaves like a real one
Your app sends the exact same API call it would in production — same headers, same body, same Sender ID. The message lands in your SMS sandbox inbox instead of a real phone. No SIM cards. No carrier accounts. No ₹40 test sprints.
No real carrier
Messages never touch a carrier network. Your test OTPs stay in the inbox.
Real-time inbox
Messages appear the instant your app fires a request. No polling needed.
One endpoint swap
Change one environment variable. Your app code stays untouched.
Full payload inspection
Sender ID, headers, body, timestamp — everything your app sent, exactly as sent.
Header validation
Define required headers and sandbox rejects broken requests automatically.
Built for teams
Shared inbox for dev, QA, and product — no more OTP screenshots on Slack.
Up and running in four steps
01
Create a project, get your endpoint
Create a new project in Zunoy Sandbox. You'll get a unique REST API endpoint — your SMS sandbox sink for that environment.
02
Swap your gateway URL
Replace your SMS provider's base URL with your Zunoy endpoint. Credentials, payload structure, and application code stay the same.
03
Trigger your app's SMS flow
Run a signup, request an OTP, place an order — anything that triggers an SMS. Your code fires the same request it always has.
04
Inspect the full payload
Open your inbox. The message is already there — Sender ID, recipient, body, headers, timestamp, raw payload.
One endpoint change. Everything else stays the same
You're not rewriting your SMS service. You're redirecting it to a safe SMS sandbox for testing. Here's what that looks like across common stacks.
Your real SMS provider and Zunoy SMS Inbox accept the same payload structure. One environment variable. That’s the entire migration.
curl --request POST \
--url https://sms.sandbox.zunoy.com/v1/send \
--header 'Authorization: Bearer YOUR_PROJECT_TOKEN' \
--header 'Content-Type: application/json' \
--data '{
"to": "+919876543210",
"sender": "YOBANK",
"body": "Your OTP is 483920. Valid for 10 minutes."
}'
GLOBAL FEED
See every test SMS the moment it arrives
Your SMS sandbox inbox updates in real time — no refresh, no polling. The moment your app fires a request, it's here. Accepted messages show full payload. Rejected messages show exactly why.
Make Sandbox reject SMS the way a real carrier would
Real carriers reject messages that don't meet their header requirements — silently, in production, at the worst possible time. Predefined Headers lets your SMS sandbox do the same in staging, so broken requests never make it to your users.
Strict mode
Headers defined. Sandbox rejects anything missing them and logs why.
Open mode
No rules set. Sandbox accepts everything. Good for early development.
Set it once at the project level. Every SMS API test request gets validated automatically from that point on.
Test your SMS templates before touching a real carrier
If you're sending SMS in India, you're working with DLT — registered templates, variable placeholders, and carrier-side rendering. Zunoy SMS Inbox mimics this entire flow so you can test OTP SMS, transactional messages, and template variable handling without a real carrier approval process.
Template Mode
Full Body Mode
YOUR APP SENDS
SANDBOX RENDERS
What developers actually use SMS Inbox for
Test OTP SMS without real delivery
Test your OTP SMS flow — request, delivery, expiry, retry — without sending a single real SMS.
Transactional SMS testing
Order confirmations, delivery alerts, payment receipts — test every trigger. No credits burned.
DLT template validation
Validate template IDs, variable keys, and formatted values before DLT registration.
Automated SMS testing
Trigger SMS flows in your test suite. Assert on received messages via the Sandbox API after every build.
console.log("SMS sent") isn't a test. It's a guess.
| FEATURES | CONSOLE.LOG | ZUNOY SMS INBOX |
|---|---|---|
Confirms SMS request fired | — | |
Shows full message body | — | |
Validates Sender ID | — | |
Checks headers were correct | — | |
Validates DLT template rendering | — | |
Visible to entire QA team | — | |
Usable in automated SMS testing | — |
You know your code fired. You don't know if it was right. That's the gap SMS sandbox closes.
COLLABORATION
Designed for QA, backend, and product teams working together
SMS testing in staging isn't a solo activity. Sandbox gives your whole team visibility into the same fake SMS gateway inbox — so no one's forwarding OTP screenshots over Slack at 6pm.
For Backend Developers
Point your app at the SMS sandbox endpoint, inspect raw payloads, validate headers, and confirm your SMS API is behaving correctly — all without a real carrier in the loop.
For QA Engineers
See every SMS your test suite triggers in real time. Validate message content, Sender IDs, and template rendering across every test run. No real phone needed.
For Product Teams
Confirm the OTP your user receives looks exactly right — correct brand name, correct format, correct copy — before it reaches a real customer.
One inbox. Every role. No coordination overhead.
Know the moment a test SMS lands — without watching the inbox
Connect your SMS Inbox to Slack, Discord, or Microsoft Teams. Every incoming SMS triggers an instant notification to your team channel — no open browser tab required
Every SMS
Get alerted on every message that hits your fake SMS gateway inbox. Useful during active test OTP SMS sessions.
By Sender ID
Only alert when SMS from a specific Sender ID arrives. Cuts noise when multiple flows are running simultaneously.
On Rejection
Get notified the moment Sandbox rejects an SMS due to a header mismatch. Catches SMS API test failures the instant they happen.
The things developers actually ask about SMS Inbox
Does Zunoy SMS Inbox actually send SMS to a phone?
No. Nothing leaves Sandbox. Your app sends the exact same API request it would to a real carrier — it lands in your SMS sandbox inbox instead of a real phone.
Can I test DLT template rendering without carrier approval?
Yes. Create your template with variable placeholders in Sandbox. Send the template ID and variable values — Sandbox resolves them and renders the final message, mimicking carrier-side rendering.
What happens if my app sends a request with missing headers?
In Strict mode, Sandbox rejects the request and logs exactly which header was missing — the same way a real carrier would, instead of silently accepting it.
Can my whole team see the same test messages?
Yes. Every SMS sent to a project inbox is visible to everyone with access — no more forwarding OTP screenshots over Slack.
Does SMS Inbox work with my existing SMS provider?
Yes. It works with Twilio, MSG91, AWS SNS, Exotel, Fast2SMS, Vonage, Textlocal, and any REST-based SMS gateway. Swap one environment variable to point at Sandbox.
Your next SMS test shouldn't cost a Rupee
Set up your SMS sandbox in under five minutes. Point your app at Zunoy's endpoint. Watch your first test OTP SMS land instantly.
No SMS credits needed
No virtual numbers to manage
No real users involved - Ever
Free forever on basic plan
Sandbox
Test Email, SMS, Webhooks & 2FA codes without touching production.
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