Token-bucket limits before abuse shows up on the bill.

FastAPI dependency rate limiting. Protect chat and extract endpoints. Pair with usage metering for spend caps.

~708 words · field guide

Your API is not an all-you-can-eat buffet. Put up a velvet rope.

Friendly fire traffic

• Retry storms.
• Demo scripts that become load tests.
• No 429 until the invoice.

The shape of the solution

TokenBucket.allow(key) as a dependency. Tune rate/capacity per route.

• Token bucket
• Per-key limits
• 429 path
• Verify

What's in the download

• ratelimit.py
• app.py
• README
• LICENSE

What Rate Limit Middleware is for (and what it isn’t)

Rate Limit Middleware lives in the API · limits lane. It’s a downloadable workshop folder — code you unzip, run in mock mode, and adapt — not a hosted product with seats, SLAs, or a customer success manager named Chad.

In plain terms: TokenBucket.allow(key) as a dependency. Tune rate/capacity per route.

If you came here for a soft-focus brand story about ‘empowering data journeys,’ you’re in the wrong harbor. This is notes from people who got tired of rebuilding the same bridge on every engagement.

The Tuesday-afternoon version of the problem

These kits start on a Tuesday afternoon. Someone asks for a ‘thin wrapper’ or a ‘quick sync.’ Three weeks later you’re debugging pagination while Slack blinks like a smoke alarm.

For this one, the pain usually shows up as: (1) Retry storms. (2) Demo scripts that become load tests. (3) No 429 until the invoice.

Your API is not an all-you-can-eat buffet. Put up a velvet rope.

429 is a feature

Better a clear limit than a silent meltdown.

Pair with metering

Rate limits pace. Metering prices. Together they save margins.

How to evaluate it without vibes

Open the README. Copy .env.example. Run the verify script or mock path. You want a boring green signal that the contract works. Flashy demos that only run on the author’s laptop are how ‘kits’ earned a bad name.

Then read the modules like a colleague’s PR. If the structure looks reusable, keep going. If it feels like generated goo, close the tab — life’s short.

You’ll see pieces aimed at: Token bucket; Per-key limits; 429 path; Verify.

A realistic first week (no hero montage)

Day 0: unzip, skim the license, run verify/mock. Day 1: point env vars at non-prod credentials if you have them. Day 2: hang it behind ADF, your app, or cron — depending on what this kit is — and watch one happy path.

Day 3 is when you stop treating it like a demo: logging, retries, secrets in a real secret store, and the inevitable ‘can we also support X?’ You own the code. Extend it. That’s the whole point of a workshop asset versus renting another logo.

If your process requires a design doc before a Dockerfile, paste the architecture from this page into the doc and skip inventing folklore from Slack threads.

Where the jokes stop

Humor is here so the page isn’t a funeral. It is not a substitute for signature checks, pagination, role gates, or private networks. If you smirked and skipped verify, that’s on both of us.

Checklist: secrets out of git, mock before prod, verify in CI if you can. The ZIP is the workshop. This page is the field notes.

Dark Lighthouse is a consulting alias with a product habit — reusable bridges because rewriting them from scratch was getting old.

Where it fits

Rate Limit Middleware is aimed at data, platform, or SaaS engineers who recognize the pain bullets above and want a deployable starting point instead of a six-week inventing contest.

It won’t replace a fully managed sync, a white-glove marketplace app, or a promise that vendors never change APIs. Sharp tools, not frozen oceans.

Wrap-up

That’s the field notes for Rate Limit Middleware. Next step is the ZIP and the verify script — not another meeting. Questions: admin@darklighthousesolutions.com.

More bridges in the same style live on the kit guides index.

FAQ

Redis?

In-memory starter — shared store when you multi-node.

User vs IP?

You choose the key.

Download on Polar if you want the ZIP · All guides