A testing tool for web pages that use APIs, which are services the page calls to send or receive data. It can replace responses, change requests, and observe the page's network traffic.

Use it to mock API results, simulate errors or offline conditions, add authentication headers, intercept requests, and inspect fetch or other network requests made by the page.

It lets you test browser behavior without always relying on a working backend or real server responses.

api-testing — Skill for Claude Code by ironbee-ai

Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo

git clone --depth 1 https://github.com/ironbee-ai/ironbee-devtools-skills

agentmods

npx agentmods add skills/ironbee-ai/ironbee-devtools-skills/api-testing

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/ironbee-ai/ironbee-devtools-skills/api-testing/github.svg)](https://agentmods.dev/skills/ironbee-ai/ironbee-devtools-skills/api-testing)

Your own site

<a href="https://agentmods.dev/skills/ironbee-ai/ironbee-devtools-skills/api-testing"><img src="https://agentmods.dev/badge/skills/ironbee-ai/ironbee-devtools-skills/api-testing/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/ironbee-ai/ironbee-devtools-skills/api-testing"><img src="https://agentmods.dev/badge/skills/ironbee-ai/ironbee-devtools-skills/api-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 89 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,744 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00089	$0.01744
Opus 5.5	$0.00036	$0.00698
Sonnet 5.5	$0.00018	$0.00349
Haiku 4.5	$0.00009	$0.00174

Measured 1mo ago against content hash fbb0371c136d, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

api-testing scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

# Trigger the API from browser (or curl), then get snapshots

skills/api-testing/SKILL.md · 215 lines

How it starts

The opening of the file, as written. The whole thing — 215 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Testing Skill

Test browser-side API integrations by mocking responses, intercepting requests, and monitoring network traffic from the page perspective.

Server-side API testing — driving real backend endpoints over HTTP/1.1+HTTP/2, gRPC, GraphQL, or WebSocket, correlating with server logs (file/Docker/Kubernetes), and asserting on database state — belongs in the backend-testing skill.

When to Use

This skill activates when:

User wants to test API integrations
User needs to mock backend responses
User wants to simulate error scenarios
User asks about request interception
User needs to test offline behavior

Capabilities

Response Mocking

ironbee-browser-devtools-cli stub mock-http-response \
  --pattern "**/api/users" \
  --response '{"action":"fulfill","status":200,"body":[{"id":1,"name":"Test"}]}'

Request Interception

ironbee-browser-devtools-cli stub intercept-http-request \
  --pattern "**/api/**" \
  --modifications '{"headers":{"Authorization":"Bearer token"}}'

Network Monitoring

ironbee-browser-devtools-cli --json o11y get-http-requests
ironbee-browser-devtools-cli --json o11y get-http-requests --resource-type fetch
ironbee-browser-devtools-cli --json o11y get-http-requests --status '{"min":400}'

Stub Management

ironbee-browser-devtools-cli stub list
ironbee-browser-devtools-cli stub clear --stub-id <id>
ironbee-browser-devtools-cli stub clear

Common Scenarios

Mock Successful Response

ironbee-browser-devtools-cli stub mock-http-response \
  --pattern "**/api/users" \
  --response '{"action":"fulfill","status":200,"body":[{"id":1,"name":"Test"}]}'

Simulate Server Error

ironbee-browser-devtools-cli stub mock-http-response \
  --pattern "**/api/checkout" \
  --response '{"action":"fulfill","status":500,"body":{"error":"Internal Server Error"}}'

Simulate 404 Not Found

ironbee-browser-devtools-cli stub mock-http-response \
  --pattern "**/api/missing" \
  --response '{"action":"fulfill","status":404,"body":{"error":"Not Found"}}'

Read the full file on GitHub · 215 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

1mo ago First seen · 215 lines · 89 tokens per session scan A fbb0371c136d

Subscribe to this mod's changes

api-testing is a skill published in the GitHub repository ironbee-ai/ironbee-devtools-skills (3 stars, last pushed 2mo ago), licensed MIT. It adds 89 tokens to every session and 1,744 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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