The All-in-One Alternative to SMTP4dev
Stop juggling multiple tools for testing emails, SMS, webhooks, and MFA. Test complete user flows in one unified sandbox — faster, safer, and built for developers.
Replace multiple testing tools with one platform
Simulate real production flows safely
Built for developers and growing teams
How Zunoy Sandbox compares to the SMTP4dev
A feature-by-feature comparison across the tools teams typically juggle before switching.
| FEATURES |  SMTP4DEV |  ZUNOY SANDBOX |
|---|---|---|
Email Inbox | ||
Authenticated Endpoints | Rarely | Required on all |
Team shared inbox | ||
Discord / Slack / Teams validation | Real-time | |
Alert integrations | Slack, Discord, Teams | |
Payload retention | Local only | Plan Based |
Public payload links | ||
Part of a full testing suite | Email + SMS + TOTP | |
SMS Inbox | ||
Webhook Inbox | ||
TOTP Testing |
SMTP4dev is great for desktop SMTP testing for local development. Sandbox helps you test the entire product experience.
Switch from SMTP4dev in under 10 minutes.
No production changes required. No risk to real users.
Create a free Zunoy Sandbox account
Sign up at sandbox.zunoy.com. No credit card required. Your account includes Email, SMS, Webhooks, and TOTP from day one.
Create an inbox and copy your SMTP credentials
Create one inbox per environment — dev, staging, QA. Copy the SMTP host, port, username, and password from your inbox settings.
Update your staging environment config
Replace your SMTP4dev SMTP host with mock-smtp.zunoy.com. Port 8136. SSL. That's the entire migration. No code changes.
Send a test email and verify it lands
Trigger any email flow in your staging environment. Open your Sandbox inbox. Email is already there — HTML rendered, scored, and visible to your whole team.
We'll migrate your team for you. Hands-on. No extra charge.
If your team is on SMTP4dev, or a custom enterprise plan and you want to switch — we handle the migration. Setup, environment config, team onboarding, and a live walkthrough. You stay focused on shipping. Available for teams of 5 or more. Typically completed in one working day.
White Glove Onboarding Process:
We audit your current staging email, SMS, webhook, and TOTP setup across all environments
We configure your Sandbox projects, inboxes, and credentials — dev, staging, QA — ready for your team to use
We update your environment configs and verify every email, SMS, and webhook flow lands correctly
Live 45-minute team walkthrough — every feature, every inbox, every alert integration
Cancel your old subscriptions with confidence — we confirm everything is working first
Book a 20-minute call and we'll handle the rest
White Glove Onboarding Process:
We audit your current staging email, SMS, webhook, and TOTP setup across all environments
We configure your Sandbox projects, inboxes, and credentials — dev, staging, QA — ready for your team to use
We update your environment configs and verify every email, SMS, and webhook flow lands correctly
Live 45-minute team walkthrough — every feature, every inbox, every alert integration
Cancel your old subscriptions with confidence — we confirm everything is working first
Book a 20-minute call and we'll handle the rest
Ready to test safely? Start your
free sandbox in under 60 seconds.
One Single Tool for - Email + SMS + Webhook + TOTP
Maintain customer trust - Test Alerts before your Users do
Setup under 5 minutes
Real human support by Zunoy Team
EMAIL INBOX — HIGHLIGHTS
Not just a message list. A full Email inspection Suite.
Not just SMTP capture. A full inspection suite with AI scoring, failure simulation, and per-inbox firewall rules that no single-channel tool offers.
HTML preview
See exactly how your email renders in Gmail, Outlook, Apple Mail, and mobile — before it reaches a single real inbox.
AI Scoring
HTML check, link check, spam analysis, performance, and AI content scoring — automatic on every email.
Failure Simulation
Six types of latency, SMTP errors, message loss, duplicates, corrupted attachments, rendering chaos. All simultaneous.
Inbox Firewall
Allowlist domains, block senders, and rate limit — per inbox. Real SMTP rejection to your app on every block.
Auto-Forward Rules
Forward emails to pre-verified addresses manually or automatically using match-any / match-all rules.
Team-Shared Inbox
Real-time for all team members. Everyone sees every email the moment it arrives — no forwarding, no screenshots.
Email is just the Start. Three more channels in the Same Workspace.
Every channel your app uses to communicate with users — tested in one place, under one account, visible to your team.
SMS Testing
Test every OTP and transactional SMS without spending a rupee on real delivery. REST API, Sender ID, SMS templates - all are included.
Webhook Testing
Get a unique URL. Point any service at it. Every payload arrives in real time — inspectable, replayable, organised by project.
Shared MFA/TOTP Inbox
Test multi-factor authentication without using a real device. Upload QR codes or secrets and share TOTP access across your QA team. No authenticator app required.
Cancel Four Subscriptions. Keep One.
Most teams using separate tools for email, SMS, webhooks, and TOTP pay $80-$200 per month across four accounts. Zunoy Sandbox replaces them all — with a free plan for small teams and straightforward pricing for larger ones.
What Teams typically Pay across Separate Tools
Maitrap / Mailosaur / Mailpit
Email Testing Tools$29-$49 / mo
SMS Sandbox Tool
SMS Testing$15-$30 / mo
Webhook Catcher
Webhook Testing$10-$25 / mo
TOTP / MFA Tool
TOTP / MFA tool$10-$20 / mo
Total Monthly Spends
$64-$124 / mo
VS
VS
Replaced by Zunoy Sandbox
FREE PLAN
$0 / Forever
Email, SMS, Webhooks, and TOTP. One account. All Four Channels. No credit card. No expiry.GROWTH / TEAM PLAN
Fraction of What you Pay Today
One subscription covers all four channels with higher limits, longer retention, and priority support.The things developers ask about switching from SMTP4dev
How is Zunoy Sandbox different from SMTP4dev?
SMTP4dev is built for desktop SMTP testing for local development. Sandbox adds AI content/spam scoring, failure simulation, inbox firewall rules, and auto-forwarding — plus SMS, webhook, and TOTP testing in the same account.
Can I import my existing SMTP4dev setup?
There's no automatic importer, but our white-glove onboarding recreates your inboxes, rules, and configuration for you — typically in one working day.
Does switching require code changes?
For SMTP-based tools, no — just point at our mock server with new credentials. For API-based tools, it's a config swap with a familiar request/response shape.
Is there a free plan like SMTP4dev's?
Yes — the free plan includes email, SMS, webhook, and TOTP testing in one account, with no credit card required.
What happens to my SMTP4dev account during the switch?
Nothing — keep it running until your Sandbox environment is verified and your team has confirmed everything works.
Beyond SMTP4dev: every channel your app needs, in one Sandbox account
Your app sends emails, SMS, webhooks, and TOTP codes. Sandbox handles all four — in one workspace, under one account, visible to your whole team.
Email Inbox
SMTP capture & AI-scored previews
SMS Inbox
Virtual numbers for OTP & transactional SMS
Webhook Inbox
Real-time payloads, replayable & shareable
TOTP Inbox
Shared MFA codes, no authenticator app needed
Sandbox
Test Email, SMS, Webhooks & 2FA codes without touching production.
Operational
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