chaos · endpoints that misbehave

HTTP endpoints that misbehave on purpose.

Point your client code, integration tests, or curious colleagues at 59 public endpoints on chaos.catastrophic.io, across 14 categories of adversity — latency, malformed payloads, broken CORS, lying Retry-After headers, and other flavors of wrong. See how your stack handles it before production does.

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Endpoints

deterministic chaos, hardcoded maxima

14 flavors of wrong

Every category covers a real failure mode your HTTP client should handle gracefully. They probably don't.

01 / 14

Agent chaos

Semantically wrong responses that pass structural validation. Tests whether agents validate content, not just shape.

02 / 14

Authentication

401 challenges with configurable WWW-Authenticate schemes.

03 / 14

CORS

Broken or missing CORS headers, including preflight failures.

04 / 14

Delivery

Responses where the wire-level delivery of the body lies — short bodies, early closes, Content-Length mismatches.

05 / 14

Discovery chaos

Meta-endpoints that serve mutated versions of standard .well-known discovery schemas.

06 / 14

Fault injection

Random failures at configurable probability.

07 / 14

Format chaos

Common-Internet-file-format misbehaviour: bytes that look like the right format but break in specific structural ways.

08 / 14

Headers & caching

Responses with misleading, excessive, or contradictory headers.

09 / 14

Latency

Slow responses, dripping streams, and delayed behavior.

10 / 14

Method handling

Servers that lie about which HTTP methods they support, or violate RFC 9110 method-response rules.

11 / 14

Pagination

Paginated responses whose metadata lies, whose pages overlap, or whose Link headers point to the wrong place.

12 / 14

Rate limiting

429 responses with configurable Retry-After headers.

13 / 14

Redirects

Redirect chains of configurable depth.

14 / 14

Status codes

Arbitrary HTTP statuses on demand.

chaos · try it

Three quick requests

Quickest way to confirm your client handles adversity. Each one fails (or succeeds-suspiciously) in a documented way.

bash

# 2 second delay before the response arrives
curl -i https://catastrophic.io/slow?ms=2000

# arbitrary status code — try anything from 100 to 599
curl -i https://catastrophic.io/status/503

# 30% chance of failure, otherwise 200
curl -i 'https://catastrophic.io/flaky?p=0.3'

import requests

# 2 second delay before the response arrives
print(requests.get('https://catastrophic.io/slow?ms=2000').status_code)

# arbitrary status code — try anything from 100 to 599
print(requests.get('https://catastrophic.io/status/503').status_code)

# 30% chance of failure, otherwise 200
print(requests.get('https://catastrophic.io/flaky', params={'p': 0.3}).status_code)

// 2 second delay before the response arrives
await fetch('https://catastrophic.io/slow?ms=2000');

// arbitrary status code — try anything from 100 to 599
console.log((await fetch('https://catastrophic.io/status/503')).status);

// 30% chance of failure, otherwise 200
console.log((await fetch('https://catastrophic.io/flaky?p=0.3')).status);

package main

import (
    "fmt"
    "net/http"
)

func main() {
    // 2 second delay before the response arrives
    http.Get("https://catastrophic.io/slow?ms=2000")

    // arbitrary status code — try anything from 100 to 599
    r, _ := http.Get("https://catastrophic.io/status/503")
    fmt.Println(r.StatusCode)

    // 30% chance of failure, otherwise 200
    r, _ = http.Get("https://catastrophic.io/flaky?p=0.3")
    fmt.Println(r.StatusCode)
}

// Cargo.toml: reqwest = { version = "0.12", features = ["blocking"] }
fn main() -> Result<(), Box> {
    // 2 second delay before the response arrives
    reqwest::blocking::get("https://catastrophic.io/slow?ms=2000")?;

    // arbitrary status code — try anything from 100 to 599
    let r = reqwest::blocking::get("https://catastrophic.io/status/503")?;
    println!("{}", r.status());

    // 30% chance of failure, otherwise 200
    println!("{}", reqwest::blocking::get("https://catastrophic.io/flaky?p=0.3")?.status());
    Ok(())
}

import java.net.URI;
import java.net.http.*;

HttpClient c = HttpClient.newHttpClient();
var discard = HttpResponse.BodyHandlers.discarding();

// 2 second delay before the response arrives
c.send(HttpRequest.newBuilder(URI.create("https://catastrophic.io/slow?ms=2000")).build(), discard);

// arbitrary status code — try anything from 100 to 599
System.out.println(c.send(HttpRequest.newBuilder(URI.create("https://catastrophic.io/status/503")).build(), discard).statusCode());

// 30% chance of failure, otherwise 200
System.out.println(c.send(HttpRequest.newBuilder(URI.create("https://catastrophic.io/flaky?p=0.3")).build(), discard).statusCode());

using var c = new HttpClient();

// 2 second delay before the response arrives
await c.GetAsync("https://catastrophic.io/slow?ms=2000");

// arbitrary status code — try anything from 100 to 599
var r = await c.GetAsync("https://catastrophic.io/status/503");
Console.WriteLine((int)r.StatusCode);

// 30% chance of failure, otherwise 200
Console.WriteLine((int)(await c.GetAsync("https://catastrophic.io/flaky?p=0.3")).StatusCode);

require 'net/http'

# 2 second delay before the response arrives
Net::HTTP.get_response(URI('https://catastrophic.io/slow?ms=2000'))

# arbitrary status code — try anything from 100 to 599
puts Net::HTTP.get_response(URI('https://catastrophic.io/status/503')).code

# 30% chance of failure, otherwise 200
puts Net::HTTP.get_response(URI('https://catastrophic.io/flaky?p=0.3')).code

# 2 second delay before the response arrives
Invoke-WebRequest 'https://catastrophic.io/slow?ms=2000'

# arbitrary status code — wrap in try/catch for non-2xx
try { Invoke-WebRequest 'https://catastrophic.io/status/503' } catch { $_.Exception.Response.StatusCode.value__ }

# 30% chance of failure, otherwise 200
try { Invoke-WebRequest 'https://catastrophic.io/flaky?p=0.3' } catch { 'failed (chaos)' }