Implement rate limiting per user and per API key

[Smartdevs17]

Description

No rate limiting exists making the API vulnerable to abuse. Implement distributed rate limiting with per-user and per-key counters.

Acceptance Criteria

• Sliding window rate limiter using Redis
• Per-API-key and per-user rate limits
• Tier-based limits (free, pro, enterprise)
• Rate limit headers (X-RateLimit-Remaining, X-RateLimit-Reset)
• Graceful 429 with Retry-After
• Rate limit analytics dashboard

Technical Scope

• backend/services/
• src/middleware/
• Edge: distributed counter accuracy, clock skew, rate limit bypass via multiple keys

[Solaristicsolar1]

@Solaristicsolar1 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

I’d like to work on this issue because I’m interested in backend security and API reliability. I’ve worked with authentication, middleware, and request handling before, and I’d love to help implement proper rate limiting for both users and API keys to improve system stability.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Solaristicsolar1 to this issue.

[drips-wave]

Congratulations, @Solaristicsolar1! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @Solaristicsolar1: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊