Catch every staging
message
before your users do.
One safe sink for emails, SMS, webhooks, and more. Route your staging communication to Sinkbox to inspect and debug – with zero risk of messaging your actual customers.
No credit card required (ever) • Setup in under 2 minutes • 100% EU Hosted
$ ./scripts/staging-billing-renewals.sh --limit=21339
[staging] Initializing nightly renewal reminders (21,339 queued)...
# Ready to run in staging environment. What could go wrong?
No credit card, no bespoke setup. Drop in your credentials and trigger your first test event.
Drop-in endpoints for SMTP, SMS, push notifications, voice IVR, and custom webhooks.
Strict data residency and privacy compliance, hosted entirely within European data centres.
Drop-in endpoints for your entire stack
Drop-in replacement for your notification stack.
No proprietary SDKs, no mock servers to maintain. Simply change your base URL and route real-world payloads into a safe sandbox.
Every channel in a single dev inbox.
Stop chasing logs across four different tabs and terminal windows. See emails, SMS codes, webhooks, and push notifications arrive live in one searchable dashboard.
Inspect full payloads & headers
Click any event to view raw JSON bodies, MIME structures, and HTTP request headers instantly.
Search & filter in real time
Query by recipient phone number, email address, topic, or endpoint path in seconds.
Verify multi-step user flows
Trace complete authentication journeys—from sign-up emails and OTP SMS codes to webhook confirmations.
Take it for a spin.
Right here,
right now.
No sign-up, no installs, no credit card. Click through example messages, test email HTML rendering, and inspect raw payloads right in your browser.
Modern apps send
more than just email.
Your product sends SMS codes, triggers webhooks, and dispatches push alerts. Here is how Sinkbox compares to legacy, email-only test servers.
Sinkbox vs Traditional Mail Catchers
| Capability / Feature |
Sinkbox
|
Traditional Mail Catchers |
|---|---|---|
|
Multi-Channel Ingestion
Catch emails, SMS messages, push notifications, voice IVR, chat, and webhook dumps in one unified stream.
|
✓ | Email only |
|
Drop-in 1-Line Config
Natively emulate REST mail APIs, SMS gateways, push services, and webhooks with zero SDK refactoring.
|
✓ | Custom mock servers & separate SDKs |
|
Branch & Ephemeral Sandboxes
Isolated project keys for local dev, CI pipelines, and preview PR environments.
|
✓ | Messy shared inboxes |
|
100% EU Data Residency & GDPR
Servers, databases, and logs located strictly within EU data centres with auto-retention purge.
|
✓ | US cloud / unclear residency |
|
Built-in HTML Linter & Spam Score
Checks links, images, syntax errors, and spam triggers automatically on every message.
|
✓ | Paid add-on or unsupported |
|
Predictable Developer Pricing
Free plan available. Straightforward pricing from €9/month with no sudden overage fees.
|
✓ | Steep paywalls & surprise bills |
Simple, transparent pricing
from solo to scale.
Free plan available, no credit card required. Upgrade as your stack complexity grows or use our unique free emergency upgrade.
Free
For single-project testing.
- ✓ 50 items / month
- ✓ 1 project
- ✓ 10 users
- ✓ 3 days retention
- ✓ 10 MB storage
- ✓ SMTP ingestion
No credit card required (ever)
Starter
For solo devs & active side-projects.
- ✓ 2K items / month
- ✓ 5 projects
- ✓ 100 users
- ✓ 2 weeks retention
- ✓ 100 MB storage
- ✓ 5 pinned items
- ✓ SMS & Email drop-in endpoints
- ✓ .eml downloads & HTTP dumps
No credit card required (ever)
Pro
For growing teams & modern SaaS.
- ✓ 10K items / month
- ✓ 20 projects
- ✓ 100 users
- ✓ 1 month retention
- ✓ 500 MB storage
- ✓ 10 pinned items
- ✓ 200 forwards / month
- ✓ Mobile Push, Voice IVR & Chat
- ✓ Custom retention per project
- ✓ FIFO auto-purge
No credit card required (ever)
Business
For high volume & compliance.
- ✓ 100K items / month
- ✓ 100 projects
- ✓ 100 users
- ✓ 1 year retention
- ✓ 5 GB storage
- ✓ 50 pinned items
- ✓ 1K forwards / month
- ✓ Outbound Webhooks & Public links
- ✓ Per-user read tracking & team rules
- ✓ Auto-forwarding rules
No credit card required (ever)
High volume or custom infrastructure needs?
Need dedicated sandboxes, SAML SSO, or higher throughput? Let's talk directly about bespoke scaling for your stack.
Frequently asked questions.
Everything you need to know about multi-channel testing, data privacy, and drop-in integration.
How does Sinkbox capture emails, SMS, and webhooks without sending them?
Sinkbox acts as a safe, central sink for all outgoing events. It accepts inbound traffic via standard SMTP credentials, drop-in REST base URLs (for email, SMS, and push), and incoming webhook endpoints. Payloads are parsed and displayed live in your project sandbox, but are never relayed to real recipients or phone numbers.
How does the 1-line drop-in replacement work?
Sinkbox emulates popular third-party provider APIs directly. Instead of refactoring your codebase or installing heavy mock libraries, simply swap your provider’s base URL (e.g. EMAIL_API_BASE or SMS_API_BASE) to Sinkbox. Your application makes standard API calls, and Sinkbox captures and visualises them in real time.
Where is my test data stored and how is GDPR handled?
100% of Sinkbox infrastructure, databases, and payload storage are hosted strictly within the European Union (EU). We never sell or share test data, and automatic retention policies purge old payloads regularly to ensure effortless GDPR compliance.
Can I automate assertions in my CI/CD test pipelines?
Yes! Sinkbox includes a comprehensive REST API built for automation. In your test suites (unit, integration, or Playwright/Cypress end-to-end runs), trigger an action, poll the Sinkbox API for the payload, and assert content, headers, or metadata in milliseconds.
How do team members and project sandboxes work?
Invite your entire engineering and QA team with zero per-seat fees. Each project gets its own isolated inboxes and API credentials, ensuring feature branches, CI pipelines, and individual developers never collide or leak payloads.
Why is there no seat fee?
Charging per seat encourages bad security habits like shared logins and leaked credentials. We want every developer and QA engineer on your team to have their own authenticated access with clear audit trails, without penalising your budget.
Can I use a project for multiple environments or customers?
Yes, but your customers won't love having their test payloads mixed with someone else's. Each project provisions isolated credentials and inbox streams, ensuring staging traffic, PR pipelines, and client data never collide.
Start catching outbound events in under two minutes.
Swap your base URL, invite your whole team with zero seat fees, and test your stack with total peace of mind.