FAQ
General Questions
What is Interface402?
The simplest way to accept x402 payments. We handle all the blockchain complexity so you don't have to. Just one API call to verify payments.
How do I get started?
Sign up at interface402.dev
Get your API key (takes 30 seconds)
Make an API call to verify payments
That's it. You're done.
Check out our Getting Started guide for code examples.
What is x402?
x402 is a payment standard that lets you accept crypto payments over regular HTTP. No wallet popups, no blockchain complexity. Just payments that work like API calls.
Learn more at x402.org
Do I need to know blockchain stuff?
Nope. That's the whole point. If you can make an HTTP request, you can use Interface402.
What blockchain does this work with?
Currently Solana. We handle all the blockchain interactions so you never have to think about it.
Getting Paid
How do I receive payments?
Just give us your wallet address. When someone pays you through x402, we verify it and you get the money. Simple.
Do I need a special wallet?
Any Solana wallet works. We recommend Phantom or Solflare if you don't have one yet.
How long does it take to get paid?
Payments confirm in 2-5 seconds on Solana. That's it. No waiting days like traditional payment processors.
What are the fees?
We don't take a cut of your payments. You just pay for the API usage. Check interface402.dev/pricing for plans.
API & Integration
Is there an SDK?
Nope, and you don't need one. It's just HTTP endpoints. Use whatever library you normally use for API calls.
Can I use this from my frontend?
No. Keep your API key on the server. Never put it in frontend code or it'll get stolen.
What if the API goes down?
We have 99.9% uptime. But if something happens, check interface402.dev/status for updates.
How many requests can I make?
Depends on your plan:
Free: 100 requests/minute
Paid: 1,000 requests/minute
Enterprise: As many as you need
See Rate Limits for details.
What happens if I go over the limit?
You'll get a 429 Too Many Requests error. Just wait a bit and try again. Or upgrade your plan.
Security
How do I keep my API key safe?
Put it in environment variables, not your code
Never commit it to GitHub
Don't put it in frontend code
Rotate it regularly
What if someone steals my key?
Go to your dashboard
Delete the compromised key
Generate a new one
Update your app
Takes like 2 minutes.
Is this secure?
Yes. We use the same security practices as payment processors. Your API calls are encrypted, payments are verified on-chain, and we never hold your funds.
Errors & Problems
I'm getting errors. What do I do?
Check our Error Handling guide. Most errors are simple fixes like:
Wrong API key
Missing required fields
Invalid wallet address
Payment verification failed
Usually means:
The payment proof is wrong
The amount doesn't match what you expected
The wallet address is incorrect
Double-check your parameters.
The API is slow
It shouldn't be. We verify payments in milliseconds. If you're seeing slowness:
Check interface402.dev/status
Make sure you're not hitting rate limits
Contact support if it persists
Support
How do I get help?
These docs: Most questions are answered here
Status page: interface402.dev/status
Twitter: @interface402
Email: [email protected]
Is there a community?
Follow us on Twitter @interface402 for updates and to chat with other developers using Interface402.
How do I report a bug?
Email [email protected] with:
What you were trying to do
What happened instead
Any error messages you got
Your API request (remove your API key first!)
Best Practices
Should I retry failed requests?
Yes, but be smart about it:
Do retry: Rate limits, network errors, timeouts
Don't retry: Invalid parameters, wrong API key, bad wallet address
Use exponential backoff (wait longer between each retry).
How do I test without real money?
Use small amounts first. Start with the minimum payment amount to make sure everything works before going live.
Should I use WebSockets?
Only if you need real-time updates. For most use cases, the regular API is fine. WebSockets are great for:
Payment dashboards
Real-time notifications
Monitoring multiple payments
See WebSocket API docs.
Any other tips?
Always validate payment amounts match what you expect
Log everything for debugging
Handle errors gracefully
Start simple, add complexity only if you need it
Read the error messages - they usually tell you exactly what's wrong
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