Rust guide — every framework

Rust rate limitingwith keys, credits, and plans.

One crate with cargo features for Axum, Actix Web, Rocket, and Warp. Each adapter checks the caller’s key, charges their credits, and applies their plan’s limit.

Start building freeRust SDK docs
  • Keys issued per customer
  • Credits that refill
  • Limits per plan, not per process

Official SDKs with drop-in middleware for the stack you already run

  • Python
  • Node.js
  • Go
  • Rust
  • PHP
  • .NET
  • Java
API requests validated
100M+
Average key validation
<5ms
Average analytics ingest
<5ms
Check and log, end to end
<10ms

The usual Rust rate limiter counts requests. It doesn’t know your customers.

The governor crate (and tower_governor, actix-governor) implements GCRA rate limiting in process — fast and correct on one server, with no notion of customers, keys, or balances.

With governortoday
  • Limiter state in one process
  • Keyed by IP address by default, not by the customer who is paying
  • No API keys: issuing, hashing, scoping, and revoking them is still yours to build
  • No credit balance: a request can’t cost 5 on one route and 1 on another, or refill each month
  • One limit for everyone — no per-plan limits for Free, Pro, and Enterprise customers
  • No per-customer usage log to answer “why was I blocked?” or bill against
With ReqKey in Rustone middleware
  • API keys issued per customer, prefixed, hashed, and revocable from the dashboard
  • A credit balance per customer — price each route, refill every hour, day, week, or month
  • Rate limits set per plan, shared by all of a customer’s keys, from 1 second to 24 hours
  • The same count on every worker, instance, and region — no Redis to run
  • Over the limit? A 429 with Retry-After, and no credits charged
  • Every request logged per customer — status, latency, endpoint — in under 5ms
Each adapter hands the handler a typed VerificationResult. See the code

Rust in three steps, one of them code.

ReqKey runs inside your API, not in front of it. Your server asks one question per request and gets an answer in under 5ms.

  1. 1

    Install the SDK

    cargo add reqkey --features axum

  2. 2

    Set your project key

    Copy it from the dashboard into REQKEY_PROJECT_KEY. It stays on your server.

  3. 3

    Add the middleware

    Every request is checked, charged, and logged before your handler runs.

main.rscargo add reqkey --features axum
use axum::{extract::Extension, routing::post, Json, Router};
use reqkey::{
    axum::ReqKeyLayer,
    middleware::{KeyLocation, Middleware, MiddlewareConfig},
    Client, VerificationResult,
};
use serde_json::{json, Value};
 
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::from_env()?;
    let config = MiddlewareConfig::builder("api_payments")
        .key_location(KeyLocation::header("X-Startup-Key"))
        .exclude_path("/health")
        .build()?;
 
    let app = Router::new()
        .route("/payments", post(create_payment))
        .layer(ReqKeyLayer::new(Middleware::new(client, config)));
 
    let listener = tokio::net::TcpListener::bind("127.0.0.1:3000").await?;
    axum::serve(listener, app).await?;
    Ok(())
}
 
async fn create_payment(Extension(decision): Extension<VerificationResult>) -> Json<Value> {
    Json(json!({ "credits_remaining": decision.credits_remaining }))
}
Also in Rust: Axum, Actix Web, Rocket, WarpFull Rust reference

Every request gets one of these answers

  • 200Valid key, credits charged — your handler runs
  • 402Out of credits
  • 403Key disabled, or not allowed on this API
  • 429Over the rate limit — no credits charged

Where ReqKey sits

Your customer
Your APIReqKey, under 5ms
Your handler

Responses go straight back to your customer. ReqKey sees the key check and the log line, nothing else.

Credits

Charge each route what it costs you.

A lookup can cost 1 credit and a render 5, from the same balance. Excluded paths are never validated, charged, or recorded. In Rust:

Per-route credits · Rust
// Exact paths or trailing-* prefixes: never validated, charged, or recorded
.exclude_path("/health")
.exclude_path("/docs/*")
 
// Or decide per request with a predicate
.should_protect(|request| request.path.starts_with("/api/"))
 
// Charge different endpoints differently (non-negative u64)
.credit_cost_resolver(|request| {
    Ok(if request.method == Method::POST { 5 } else { 1 })
})

Rate limits

Set limits on plans, not in code.

Your Rust code never hard-codes a number. Each plan carries its credits, refill, and rate limit; moving a customer to Pro changes all three with no deploy.

PlanCreditsRate limit
Free1,000 / month5 req / s
Pro50,000 / month50 req / s
Scale1,000,000 / month500 req / s
429Over the limit, a call is answered with Retry-After and costs nothing — no credits and no quota.

Example plans. You name them and pick the numbers.

Notes for Rust teams hit in production.

Cargo features

Only the adapter you enable is compiled — axum, actix-web, rocket, or warp.

Async and blocking

An async Client for Tokio and a blocking SyncClient for scripts and workers.

TLS your way

Rustls by default, or native-tls with --no-default-features.

Rust rate limiting: the questions teams ask.

Something else? Ask the team or read the docs.

  • No. The default build is the client only; frameworks are opt-in features.

  • Yes — the blocking SyncClient needs no async runtime.

  • On their plan or on the customer (consumer) in ReqKey — a number of requests per window from 1 second to 24 hours, shared by all of that customer’s keys. Your Rust code never hard-codes a limit, so upgrading a customer is a dashboard change, not a deploy.

  • A check averages under 5ms. ReqKey runs inside your app as middleware, not as a gateway in front of it, so responses go straight back to your customer.

  • You choose: fail closed and answer 503, or fail open and let requests through. Invalid keys are denied either way, and a validation is never retried, so no one is charged twice.

Guides for each Rust framework.

Other languages

Ship API keys in Rustin five minutes.

Free for your first 5 million requests every month. No card, no gateway, no rewrite.

Start building freeRead the docs