Whistle website screenshot

Whistle

Whistle is a cross-platform HTTP, HTTPS, HTTP/2, WebSocket, and TCP debugging proxy built on Node.js. It enables developers to inspect, intercept, modify, and replay network traffic through a rule-based configuration system with a built-in web UI.

Whistle publishes 1 API on the APIs.io network. Tagged areas include Debugging Proxy, Proxy, Network Debugging, HTTP, and WebSocket.

The Whistle catalog on APIs.io includes 1 JSON-LD context and 1 Spectral governance ruleset.

Whistle’s developer surface includes documentation, getting-started guide, GitHub presence, and 8 more developer resources.

🌐 Visit website 📡 Source on GitHub
24.9/100 emerging ▬ flat Agent 4/100 human only self hosted · MIT Full breakdown ↓
scored 2026-10-04 · rubric v0.23.0
AccessFreemium
1 API
Debugging ProxyProxyNetwork DebuggingHTTPWebSocketDeveloper Tools

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-10-04 · rubric v0.23.0
Composite quality — 24.9/100 · emerging
Contract Quality 7.1 / 21
Developer Ergonomics 3.6 / 17
Access Clarity 2.7 / 17
Operational Transparency 1.2 / 11
Contract Governance 2.4 / 10
Discoverability 4.9 / 9
Regulatory Posture 1.6 / 15
Agent readiness — 4/100 · human only
Machine-Readable Contract 0 / 18
Agentic Access Contract 0 / 10
Documented Reversibility 0 / 6
MCP Server 0 / 12
Machine-Readable Auth 0 / 10
Idempotency 0 / 9
Stable Error Semantics 0 / 8
Request/Response Examples 7 / 7
Rate-Limit Signaling 7 / 7
Typed Event Surface 0 / 6
Agent Skills 0 / 5
Well-Known Catalog 0 / 4
Consent & Bot Identity 0 / 3
A2A Agent Card 0 / 8
Dry-Run / Simulate Mode 0 / 4
Delegated User Identity 0 / 6
Protected Resource Metadata 0 / 5
Registration Without a Human 0 / 6
Agentic Commerce Well-Known Document 0 / 5
Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.
Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.
The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/whistle: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 1

Individual APIs this provider publishes, each with its own machine-readable definition.

Whistle

Whistle is a cross-platform HTTP, HTTPS, HTTP/2, WebSocket, and TCP debugging proxy tool. It lets developers intercept, inspect, and modify network traffic using a rule-based co...

Pricing Plans 1

Published pricing tiers and plan structures.

Whistle Plans Pricing

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Whistle Rate Limits

5 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Whistle Finops

FINOPS

Semantic Vocabularies 1

JSON-LD contexts and semantic vocabularies used across these APIs.

Whistle Context

9 classes · 15 properties

JSON-LD

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

Whistle API Rules

5 rules · 4 warnings 1 info

SPECTRAL

JSON Schema 2

Standalone JSON Schema definitions for this provider's data models.

Whistle Plugin

6 properties

JSON SCHEMA

Whistle Rule

4 properties

JSON SCHEMA

JSON Structure 1

JSON Structure definitions describing this provider's data shapes.

Whistle Rule Structure

3 properties

JSON STRUCTURE

Examples 1

Example request and response payloads for these APIs.

Whistle Rule Example

3 fields

EXAMPLE

Security Posture 1

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Whistle Domain Security

TLSv1.3

SECURITY

Resources

Get Started 1

Portal, sign-up, and the first successful call

GettingStarted
GettingStarted

Documentation 1

Reference material describing how the API behaves

Documentation
Documentation

Build 6

SDKs, sample code, and the tooling you integrate with

GitHubOrganization
GitHubOrganization
 GitHub
GitHub
 NPM
NPM
 DesktopClient
DesktopClient
 ChromeExtension
ChromeExtension
 PluginScaffolding
PluginScaffolding

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity
DomainSecurity

Company 2

The organization behind the API

LinkedIn
LinkedIn
 Website
Website

Source (apis.yml)

apis.yml Raw ↑ 
aid: whistle
name: Whistle
description: Whistle is a cross-platform HTTP, HTTPS, HTTP/2, WebSocket, and TCP debugging proxy built on Node.js. It enables
  developers to inspect, intercept, modify, and replay network traffic through a rule-based configuration system with a built-in
  web UI.
type: Index
deliveryModel:
  model: self-hosted
  license: MIT
  license_evidence:
    repo: avwo/whistle
    spdx: MIT
    stars: 15709
  open_source: true
  commercial: false
  callable_host: false
  label: Self-hosted open source · you run it yourself
  confidence: medium
  source:
  - repository-license
  generated: '2026-09-25'
  method: derived
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: medium
  source:
  - plans
  generated: '2026-07-22'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/whistle.png
tags:
- Debugging Proxy
- Proxy
- Network Debugging
- HTTP
- WebSocket
- Developer Tools
tags_raw:
- Debugging Proxy
- Proxy
- Network Debugging
- HTTP
- HTTPS
- WebSocket
- Developer Tools
url: https://raw.githubusercontent.com/api-evangelist/whistle/refs/heads/main/apis.yml
created: '2026-03-27'
modified: '2026-05-03'
specificationVersion: '0.23'
apis:
- aid: whistle:whistle
  name: Whistle
  description: Whistle is a cross-platform HTTP, HTTPS, HTTP/2, WebSocket, and TCP debugging proxy tool. It lets developers
    intercept, inspect, and modify network traffic using a rule-based configuration system. Features include request/response
    modification, local file mapping, API mocking, remote debugging with Weinre, request replay via a built-in Composer, plugin
    support, and a web-based UI.
  humanURL: https://wproxy.org/whistle/
  baseURL: http://localhost:8899
  tags:
  - Debugging Proxy
  - Proxy
  - Network Debugging
  - HTTP
  - WebSocket
  - Developer Tools
  - API Mocking
  - Request Replay
  tags_raw:
  - Debugging Proxy
  - Proxy
  - Network Debugging
  - HTTP
  - HTTPS
  - WebSocket
  - Developer Tools
  - API Mocking
  - Request Replay
  properties:
  - type: Documentation
    url: https://wproxy.org/en/docs/
  - type: GettingStarted
    url: https://wproxy.org/en/docs/getting-started.html
  - type: GitHub
    url: https://github.com/avwo/whistle
  - type: NPM
    url: https://www.npmjs.com/package/whistle
  - type: JSONSchema
    url: https://raw.githubusercontent.com/api-evangelist/whistle/main/json-schema/whistle-rule-schema.json
  - type: JSONSchema
    url: https://raw.githubusercontent.com/api-evangelist/whistle/main/json-schema/whistle-plugin-schema.json
  - type: JSONStructure
    url: https://raw.githubusercontent.com/api-evangelist/whistle/main/json-structure/whistle-rule-structure.json
  - type: JSONLDContext
    url: https://raw.githubusercontent.com/api-evangelist/whistle/main/json-ld/whistle-context.jsonld
  - type: Examples
    url: https://raw.githubusercontent.com/api-evangelist/whistle/main/examples/whistle-rule-example.json
  - type: Vocabulary
    url: https://raw.githubusercontent.com/api-evangelist/whistle/main/vocabulary/whistle-vocabulary.yml
  contact:
  - FN: Whistle Team
    url: https://github.com/avwo/whistle
  features:
  - Request and response interception and modification
  - HTTP, HTTPS, HTTP/2, WebSocket, TCP support
  - Rule-based traffic modification
  - Local file mapping and API mocking
  - Built-in Weinre for remote DOM inspection
  - Request Composer for replay and editing
  - Plugin extensibility system
  - Multiple proxy modes: HTTP, HTTPS, Socks, reverse proxy
  - Cross-platform: macOS, Windows, Linux
  - Web-based management UI at localhost:8899
  use-cases:
  - Frontend development API proxying
  - Mobile app network debugging
  - CORS configuration testing
  - Request/response modification during development
  - API mocking with local JSON files
  - Remote debugging of web pages on devices
  - Traffic inspection and analysis
  integrations:
  - Chrome Extension ZeroOmega for proxy switching
  - Weinre for remote DOM inspection
  - Node.js NPM module integration
  - Desktop client via whistle-client
common:
- type: DomainSecurity
  url: security/whistle-domain-security.yml
- type: LinkedIn
  url: https://www.linkedin.com/company/whistle-labs
- type: Website
  url: https://wproxy.org/whistle/
- type: Documentation
  url: https://wproxy.org/en/docs/
- type: GettingStarted
  url: https://wproxy.org/en/docs/getting-started.html
- type: GitHubOrganization
  url: https://github.com/avwo
- type: GitHub
  url: https://github.com/avwo/whistle
- type: NPM
  url: https://www.npmjs.com/package/whistle
- type: DesktopClient
  url: https://github.com/avwo/whistle-client
- type: ChromeExtension
  url: https://github.com/avwo/whistle-for-chrome
- type: PluginScaffolding
  url: https://github.com/avwo/lack
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

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