Rate Limiting
Stop one client from ruining it for everyone.
What it adds
Throttling on the endpoints that get abused: auth, search, exports, and public forms.
What your agent is told to do
4
What your agent is told to do
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Identify the endpoints worth protecting: sign-in, sign-up, password reset, search, exports, and anything unauthenticated.
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Limit by a stable identifier — user ID where signed in, IP otherwise. Be aware IP is shared behind NAT and proxies.
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Return 429 with a Retry-After header. Do not silently drop the request.
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Be far stricter on authentication endpoints. Sign-in is where credential stuffing happens.
Edge cases it handles
5
Edge cases it handles
5- Get the client IP correctly behind a proxy or CDN — a spoofable header is not a limit.
- Do not rate-limit your own health checks, webhooks, or internal jobs into failure.
- The limiter must fail OPEN or CLOSED deliberately — decide which, because it will fail.
- Legitimate bursts (a user opening ten tabs) must not lock out a real customer.
- Never leak whether an email exists via differential rate limiting on sign-in.
Definition of done
8
Definition of done
8- Auth, search, export, and public endpoints are limited.
- 429 responses include Retry-After.
- The client IP is derived correctly behind proxies.
- Webhooks and health checks are exempt.
- Failure behaviour is a deliberate decision.
- Limits don't reveal whether an account exists.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
Password Generator
Password Generator
Offer a strong password in one click wherever someone sets or changes credentials.
What it does
A generate control on password fields that produces a strong value, shows it, and hands it to the user safely.
How it works
- 1 Add the control to every place a password is set: sign-up, password change, password reset completion, and any admin screen that provisions credentials for someone else.
- 2 Generate the value in the browser using the platform's cryptographic random source. The value must never be produced on the server or sent anywhere.
- 3 Reveal the generated password by default so the user can record it, and offer a regenerate control beside it. A hidden generated password that the user cannot see is a password they will immediately reset.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/password-generator
Data Integrity Constraints
Data Integrity Constraints
Enforce your important rules in the database, not just in the form.
What it does
Database-level uniqueness, foreign key, check, and not-null constraints backing the business rules the application currently only validates in code.
How it works
- 1 Inventory the rules the app relies on — required fields, uniqueness, valid enum values, positive amounts, referential links — and note which exist only in application code.
- 2 Before adding each constraint, query for rows that already violate it and decide explicitly whether to fix, delete, or exclude them. Every mature database has violating legacy rows.
- 3 Add constraints in a way that does not hold a long exclusive lock: create indexes concurrently, add checks as NOT VALID and validate them in a second step.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/data-integrity-constraints
Session Management
Session Management
Let users see and revoke their own sessions.
What it does
A list of active sessions with device and location, and one-click revocation.
How it works
- 1 Store sessions as records with a user agent, IP, and last-seen timestamp.
- 2 Show the user their active sessions and let them revoke any of them — and all others at once.
- 3 Mark the current session clearly so they don't sign themselves out by accident.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/session-management
How it works
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1
Copy the link
Grab the Markdown instruction URL for this feature.
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Give it to your AI
Paste it into Claude Code, Cursor, v0, Lovable — whatever you build with.
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It inspects, then implements
Your agent reads your existing app first, then adds the feature to fit it.
Works with your stack
These instructions are written to adapt. They tell the agent to detect your framework, match your existing design system, and reuse what you already have — rather than assuming a particular stack.
Need it tighter than that? Customize the feature and tell it exactly what you're running.