traffic2openapi

Traffic2OpenAPI

Generate OpenAPI 3.0/3.1/3.2 specifications from HTTP traffic logs.

Documentation | Getting Started

Traffic2OpenAPI captures HTTP request/response traffic from multiple sources (HAR files, Playwright, proxy captures), normalizes it to a shared Intermediate Representation (IR), and generates OpenAPI specs through intelligent inference.

Quick Start

# Install
go install github.com/grokify/traffic2openapi/cmd/traffic2openapi@latest

# Convert HAR file to IR format
traffic2openapi convert har -i recording.har -o traffic.ndjson

# Convert Postman collection to IR format
traffic2openapi convert postman -i collection.json -o traffic.ndjson

# Generate OpenAPI spec from IR
traffic2openapi generate -i traffic.ndjson -o openapi.yaml

# Generate static HTML documentation site
traffic2openapi site -i traffic.ndjson -o ./site/

# Validate IR files
traffic2openapi validate ./logs/

Features

• 📥 Multi-source input: HAR files, Postman collections, Playwright captures, proxy logs, or manual capture
• 🧠 Intelligent inference: Automatically detects path parameters, query params, schemas
• 📋 OpenAPI 3.0/3.1/3.2: Generate specs for any version
• 📦 Multi-version output: Generate specs for multiple OpenAPI versions simultaneously
• ✅ Spec validation: Validate generated specs using libopenapi
• 🔍 Format detection: Email, UUID, date-time, URI, IPv4/IPv6
• 🏷️ Type inference: String, integer, number, boolean, array, object
• 📊 Required/optional: Tracks field presence across requests
• 🔒 Security detection: Automatically detects Bearer, Basic, API Key authentication
• 📑 Pagination detection: Identifies page/limit/offset/cursor patterns
• ⏱️ Rate limit detection: Captures X-RateLimit-* headers from responses
• 🔄 Provider pattern: Symmetric read/write for IR records (NDJSON, Gzip, Storage, Channel)
• 📡 LoggingTransport: Capture HTTP traffic from Go http.Client
• 🛠️ Fluent builder API: Programmatically construct OpenAPI specs with openapibuilder package
• ⚖️ Spec comparison: Diff two OpenAPI specs to detect breaking changes
• 🌐 Documentation server: Serve specs with Swagger UI or Redoc
• 📝 Static site generator: Generate HTML documentation from traffic logs
• 👁️ Watch mode: Auto-regenerate specs when IR files change

Architecture

┌──────────────────────────────────────────────────────────────────────────────┐
│                              TRAFFIC SOURCES                                 │
├──────────────────┬──────────────────┬──────────────────┬─────────────────────┤
│ Browser DevTools │ Test Automation  │ Go http.Client   │ Proxy Captures      │
│ (HAR export)     │ Playwright, etc  │ LoggingTransport │ mitmproxy, Charles  │
└────────┬─────────┴────────┬─────────┴────────┬─────────┴───────────┬─────────┘
         │                  │                  │                     │
         ▼                  ▼                  ▼                     ▼
┌──────────────────────────────────────────────────────────────────────────────┐
│                       ADAPTER LAYER (source-specific)                        │
│                  HAR Converter | Playwright Adapter | IR Writer              │
└─────────────────────────────────────┬────────────────────────────────────────┘
                                      │
                                      ▼
┌──────────────────────────────────────────────────────────────────────────────┐
│                    IR (Intermediate Representation)                          │
│                       JSON Schema v1 contract                                │
└─────────────────────────────────────┬────────────────────────────────────────┘
                                      │
                                      ▼
┌──────────────────────────────────────────────────────────────────────────────┐
│                           GO CORE ENGINE                                     │
│    IR Reader → Endpoint Clustering → Schema Inference → OpenAPI Generator    │
└─────────────────────────────────────┬────────────────────────────────────────┘
                                      │
                                      ▼
                           OpenAPI 3.0/3.1/3.2 Spec

Adapter Fidelity Comparison

Different traffic sources capture different levels of detail:

Adapter	Req Headers	Req Body	Res Headers	Res Body	Query	Timing	Docs	Setup
HAR Files	✅	✅	✅	✅	✅	✅	❌	Low
Postman	✅	✅	✅	✅	✅	❌	✅	Low
Playwright	✅	✅	✅	✅	✅	✅	❌	Low
LoggingTransport	✅	✅	✅	✅	✅	✅	❌	Low
mitmproxy	✅	✅	✅	✅	✅	✅	❌	Medium

Legend: ✅ Full support | ⚠️ Partial/Limited | ❌ Not available

Docs column: Postman collections preserve descriptions, tags (from folders), and other documentation fields.

IR (Intermediate Representation)

The IR is the shared contract between all traffic sources and the Go processing engine. It supports two formats:

Format	Use Case	File Extension
Batch	File-based processing, batch uploads	.json
NDJSON	Streaming, large datasets	.ndjson

Schema Location

• JSON Schema: schemas/ir.v1.schema.json
• Examples: examples/

Batch Format

{
  "version": "ir.v1",
  "metadata": {
    "generatedAt": "2024-12-30T10:00:00Z",
    "source": "manual",
    "recordCount": 2
  },
  "records": [
    {
      "id": "req-001",
      "timestamp": "2024-12-30T09:00:00Z",
      "request": {
        "method": "GET",
        "host": "api.example.com",
        "path": "/users",
        "query": { "limit": "10" }
      },
      "response": {
        "status": 200,
        "contentType": "application/json",
        "body": { "users": [], "total": 0 }
      }
    }
  ]
}

NDJSON Format (Streaming)

{"id":"req-001","request":{"method":"GET","host":"api.example.com","path":"/users"},"response":{"status":200,"body":{"users":[]}}}
{"id":"req-002","request":{"method":"POST","host":"api.example.com","path":"/users","body":{"name":"Bob"}},"response":{"status":201,"body":{"id":"456"}}}

IR Record Fields

Required Fields

Field	Type	Description
request.method	string	HTTP method (GET, POST, PUT, PATCH, DELETE, etc.)
request.path	string	Raw request path without query string
response.status	integer	HTTP status code (100-599)

Optional Fields

Field	Type	Description
id	string	Unique record identifier
timestamp	string	ISO 8601 timestamp
source	string	Adapter type: har, playwright, proxy, manual
request.scheme	string	http or https
request.host	string	Request host header
request.pathTemplate	string	Normalized path with parameters (e.g., /users/{id})
request.pathParams	object	Extracted path parameter values
request.query	object	Query parameters
request.headers	object	Request headers (lowercase keys)
request.contentType	string	Content-Type header
request.body	any	Parsed request body (object, array, string, or null)
response.headers	object	Response headers
response.contentType	string	Response Content-Type
response.body	any	Parsed response body
durationMs	number	Round-trip time in milliseconds

Go Package

The pkg/ir package provides Go types and utilities for working with IR data.

Reading IR Files

import "github.com/grokify/traffic2openapi/pkg/ir"

// Read from file (auto-detects format by extension)
records, err := ir.ReadFile("traffic.ndjson")

// Read from directory (all .json and .ndjson files)
records, err := ir.ReadDir("./logs/")

// Stream large NDJSON files
f, _ := os.Open("large-file.ndjson")
recordCh, errCh := ir.StreamNDJSON(f)
for record := range recordCh {
    // Process each record
}

Writing IR Files

// Write to batch JSON format
err := ir.WriteFile("output.json", records)

// Write to NDJSON format
err := ir.WriteFile("output.ndjson", records)

// Stream writes for large datasets
w, _ := ir.NewNDJSONFileWriter("output.ndjson")
defer w.Close()
for _, record := range records {
    w.Write(&record)
}

Creating Records Programmatically

// Using the builder pattern
record := ir.NewRecord(ir.RequestMethodPOST, "/api/users", 201).
    SetID("req-001").
    SetHost("api.example.com").
    SetRequestBody(map[string]string{"name": "Alice"}).
    SetResponseBody(map[string]interface{}{"id": "123", "name": "Alice"}).
    SetDuration(45.2)

// Create a batch
batch := ir.NewBatch([]ir.IRRecord{*record})

Inference Engine

The pkg/inference package analyzes IR records and infers API structure.

Features

• Path Template Inference: Converts /users/123 to /users/{userId}
  • Detects UUIDs, numeric IDs, hashes, dates
  • Context-aware naming with 180+ resource patterns (e.g., /users/123 → {userId}, /orders/456 → {orderId})
• Schema Inference: Builds JSON Schema from request/response bodies
  • Type detection (string, integer, number, boolean, array, object)
  • Format detection (email, uuid, date-time, uri, ipv4, ipv6)
  • Optional vs required field tracking
• Security Detection: Automatically detects authentication schemes
  • Bearer token (with JWT format detection)
  • Basic authentication
  • API key headers (X-API-Key, X-Auth-Token, etc.)
  • Outputs OpenAPI securitySchemes component
• Pagination Detection: Identifies pagination patterns from query parameters
  • Page/limit (offset-based)
  • Cursor/after/before (cursor-based)
  • Tracks min/max values and examples
• Rate Limit Detection: Captures rate limiting from response headers
  • X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset
  • Retry-After headers
• Endpoint Clustering: Groups requests by method + path template

Usage

import (
    "github.com/grokify/traffic2openapi/pkg/inference"
    "github.com/grokify/traffic2openapi/pkg/openapi"
)

// Infer from IR files
result, err := inference.InferFromDir("./logs/")

// Or process records directly
engine := inference.NewEngine(inference.DefaultEngineOptions())
engine.ProcessRecords(records)
result := engine.Finalize()

// Generate OpenAPI spec
options := openapi.DefaultGeneratorOptions()
options.Title = "My API"
options.Version = openapi.Version31

spec := openapi.GenerateFromInference(result, options)

// Write to file
openapi.WriteFile("openapi.yaml", spec)

OpenAPI Generation

The pkg/openapi package generates OpenAPI 3.0/3.1 specifications.

Supported Versions

Version	Description
Version31	OpenAPI 3.1.0 (default) - Full JSON Schema 2020-12
Version30	OpenAPI 3.0.3 - For compatibility
Version32	OpenAPI 3.2.0 - Latest specification

Output Formats

// Write to file (format detected by extension)
openapi.WriteFile("spec.yaml", spec)  // YAML
openapi.WriteFile("spec.json", spec)  // JSON

// Convert to string
yamlStr, _ := openapi.ToString(spec, openapi.FormatYAML)
jsonStr, _ := openapi.ToString(spec, openapi.FormatJSON)

OpenAPI Builder

The pkg/openapibuilder package provides a fluent API for programmatically constructing OpenAPI specifications.

Basic Usage

import "github.com/grokify/traffic2openapi/pkg/openapibuilder"

spec, err := openapibuilder.NewSpec(openapibuilder.Version310).
    Title("Pet Store API").
    Version("1.0.0").
    Server("https://api.petstore.io/v1").
    Components().
        Schema("Pet", openapibuilder.ObjectSchema().
            Property("id", openapibuilder.IntegerSchema().Format("int64")).
            Property("name", openapibuilder.StringSchema()).
            Required("id", "name")).
        SecurityScheme("bearerAuth").BearerAuth().BearerFormat("JWT").Done().
    Done().
    Path("/pets").
        Get().
            Summary("List all pets").
            OperationID("listPets").
            Response(200).Description("A list of pets").
                JSON(openapibuilder.ArraySchema(openapibuilder.RefSchema("Pet"))).Done().
        Done().
    Done().
    Build()

Multi-Version Output

Generate the same spec in multiple OpenAPI versions:

import "github.com/grokify/traffic2openapi/pkg/openapi/convert"

// Generate for all supported versions
output, err := convert.AllVersions(spec)

// Or specific versions
output, err := convert.NewMultiVersionOutput(spec,
    convert.Version303, convert.Version310, convert.Version320)

// Write all versions to files
output.WriteFilesToDir("./output", "api", openapi.FormatYAML)
// Creates: api-3.0.3.yaml, api-3.1.0.yaml, api-3.2.0.yaml

HAR Adapter

The pkg/har package converts HAR (HTTP Archive) files to IR format.

Supported Sources

HAR is a standard format supported by:

• Browser DevTools - Chrome, Firefox, Safari (Network tab → Save as HAR)
• Playwright - Built-in recordHar option
• Puppeteer - Via Chrome DevTools Protocol
• Charles Proxy - File → Export Session as HAR
• Fiddler - File → Export → HTTPArchive
• mitmproxy - mitmdump --save-stream-file
• Postman - Collection export

CLI Usage

# Convert a single HAR file
traffic2openapi convert har -i recording.har -o traffic.ndjson

# Convert multiple HAR files from a directory
traffic2openapi convert har -i ./har-files/ -o traffic.ndjson

# Filter by host
traffic2openapi convert har -i recording.har -o traffic.ndjson --host api.example.com

# Filter by method
traffic2openapi convert har -i recording.har -o traffic.ndjson --method POST

# Generate OpenAPI from HAR
traffic2openapi convert har -i recording.har -o traffic.ndjson
traffic2openapi generate -i traffic.ndjson -o openapi.yaml

Browser & Test Automation Capture

Capture HTTP traffic from browsers and test automation frameworks like Playwright, Cypress, and Puppeteer.

Supported Methods

Method	Tool	Streaming	Best For
HAR Export	DevTools, Playwright	No	Post-hoc analysis
Playwright IR Plugin	Playwright	Yes	Real-time test capture
Cypress Intercept	Cypress	Yes	E2E test suites
Puppeteer CDP	Puppeteer	Yes	Headless automation

Quick Example (Playwright)

// Record HAR during tests
const context = await browser.newContext({
  recordHar: { path: 'traffic.har', content: 'embed' }
});
await page.goto('https://api.example.com');
await context.close();  // HAR written here

// Convert to IR and generate spec
// $ traffic2openapi convert har -i traffic.har -o traffic.ndjson
// $ traffic2openapi generate -i traffic.ndjson -o openapi.yaml

For real-time streaming and Playwright event-based capture, see README_BROWSER.md.

CLI Usage

Convert Command

Convert traffic logs to IR format:

# Convert HAR file to IR
traffic2openapi convert har -i recording.har -o traffic.ndjson

# Convert Postman collection to IR
traffic2openapi convert postman -i collection.json -o traffic.ndjson

# With Postman variable substitution
traffic2openapi convert postman -i collection.json -o traffic.ndjson \
    --var baseUrl=https://api.example.com \
    --var apiKey=sk-xxx

Generate Command

Generate OpenAPI specs from IR files:

# Generate OpenAPI 3.1 spec from IR files (YAML)
traffic2openapi generate -i ./logs/ -o openapi.yaml

# Generate OpenAPI 3.0 spec (JSON)
traffic2openapi generate -i ./logs/ -o api.json --version 3.0

# Generate with custom title and servers
traffic2openapi generate -i ./logs/ -o api.yaml \
  --title "My API" \
  --api-version "2.0.0" \
  --server https://api.example.com

# Watch mode - auto-regenerate on file changes
traffic2openapi generate -i ./logs/ -o api.yaml --watch

Validate Command

Validate IR files:

# Validate IR files
traffic2openapi validate ./logs/

# Validate with verbose output
traffic2openapi validate ./logs/ --verbose

Validate-Spec Command

Validate OpenAPI specification files using libopenapi:

# Validate a single OpenAPI spec
traffic2openapi validate-spec openapi.yaml

# Validate all specs in a directory
traffic2openapi validate-spec ./specs/

# Verbose output with warnings
traffic2openapi validate-spec openapi.yaml --verbose

# Strict mode (treat warnings as errors)
traffic2openapi validate-spec openapi.yaml --strict

Merge Command

Merge multiple IR files or OpenAPI specs:

# Merge IR files with deduplication
traffic2openapi merge -i file1.ndjson -i file2.ndjson -o merged.ndjson --dedupe

# Merge OpenAPI specs
traffic2openapi merge --openapi -i spec1.yaml -i spec2.yaml -o merged.yaml

Diff Command

Compare two OpenAPI specifications:

# Compare two specs
traffic2openapi diff old.yaml new.yaml

# Output as JSON (for CI/CD)
traffic2openapi diff old.yaml new.yaml --format json

# Only show breaking changes
traffic2openapi diff old.yaml new.yaml --breaking-only

# Exit with non-zero code if breaking changes found
traffic2openapi diff old.yaml new.yaml --breaking-only --exit-code

Serve Command

Serve OpenAPI spec with interactive documentation:

# Serve with Swagger UI (default)
traffic2openapi serve openapi.yaml

# Serve on a specific port
traffic2openapi serve openapi.yaml --port 8080

# Serve with Redoc
traffic2openapi serve openapi.yaml --ui redoc

# Auto-reload when spec changes
traffic2openapi serve openapi.yaml --watch

Site Command

Generate a static HTML documentation site from IR traffic logs:

traffic2openapi site -i <input_file_or_dir> -o <output_dir> [flags]

# Generate site with default settings
traffic2openapi site -i traffic.ndjson -o ./site/

# With custom title
traffic2openapi site -i traffic.ndjson -o ./site/ --title "My API Docs"

# From directory of IR files
traffic2openapi site -i ./logs/ -o ./docs/

Features:

• Index page: Lists all endpoints with method badges and status codes
• Endpoint pages: Detailed view of each endpoint grouped by status code
• Deduped view: Collapsed view showing all seen parameter values (e.g., userId: 123, 456)
• Distinct view: Individual requests with full details
• Path template detection: Automatically detects parameters like /users/{userId}
• Light/dark mode: Toggle with localStorage persistence
• Copy buttons: One-click JSON copying
• Syntax highlighting: Color-coded JSON bodies

Generate Command Options

Flag	Short	Default	Description
--input	-i	(required)	Input file or directory
--output	-o	stdout	Output file path
--version	-v	3.1	OpenAPI version: 3.0, 3.1, or 3.2
--versions			Multiple versions (comma-separated: 3.0,3.1,3.2)
--all-versions		false	Generate all supported versions
--format	-f	auto	Output format: json or yaml
--title		Generated API	API title
--description			API description
--api-version		1.0.0	API version
--server			Server URL (repeatable)
--include-errors		true	Include 4xx/5xx responses
--watch	-w	false	Watch for file changes and regenerate
--debounce		500ms	Debounce interval for watch mode
--skip-validation		false	Skip validation of generated spec

Project Structure

traffic2openapi/
├── cmd/
│   └── traffic2openapi/     # CLI application
│       ├── main.go          # Entry point
│       ├── root.go          # Root command
│       ├── generate.go      # Generate command (with watch mode)
│       ├── validate.go      # Validate command
│       ├── convert_har.go   # Convert command (HAR)
│       ├── convert_postman.go # Convert command (Postman)
│       ├── merge.go         # Merge command (IR/OpenAPI)
│       ├── diff.go          # Diff command (OpenAPI comparison)
│       ├── serve.go         # Serve command (Swagger UI/Redoc)
│       └── site.go          # Site command (static HTML generator)
├── pkg/
│   ├── ir/                  # IR types and I/O
│   │   ├── ir_gen.go        # Generated types from JSON Schema
│   │   ├── ir.go            # Batch type, helpers
│   │   ├── reader.go        # File/dir reading, streaming
│   │   └── writer.go        # File writing, streaming
│   ├── har/                 # HAR file parsing
│   │   └── har.go           # HAR → IR conversion
│   ├── postman/             # Postman collection parsing
│   │   ├── converter.go     # Postman → IR conversion
│   │   └── reader.go        # File reading utilities
│   ├── inference/           # Traffic analysis
│   │   ├── engine.go        # Main orchestrator
│   │   ├── endpoint.go      # Endpoint clustering
│   │   ├── path.go          # Path template inference
│   │   ├── schema.go        # JSON Schema inference
│   │   ├── detection.go     # Security, pagination, rate limit detection
│   │   ├── types.go         # Internal types
│   │   └── helpers.go       # Utility functions
│   ├── openapi/             # OpenAPI generation
│   │   ├── generator.go     # Spec builder
│   │   ├── types.go         # OpenAPI 3.x types
│   │   ├── writer.go        # JSON/YAML output
│   │   ├── convert/         # Multi-version conversion
│   │   └── validate/        # Spec validation (libopenapi)
│   ├── openapibuilder/      # Fluent builder API
│   └── sitegen/             # Static HTML site generator
│       ├── engine.go        # Site engine (wraps inference)
│       ├── generator.go     # HTML generation
│       ├── dedup.go         # Deduplication logic
│       ├── templates.go     # HTML templates
│       └── assets/          # CSS and JavaScript
├── pkg/adapters/playwright/ # Playwright adapters
│   ├── python/              # Python package
│   └── typescript/          # TypeScript package
├── schemas/
│   └── ir.v1.schema.json    # IR JSON Schema
├── examples/
│   ├── sample-batch.json    # Batch format example
│   ├── sample-stream.ndjson # NDJSON format example
│   └── har/                 # HAR file examples
│       └── sample.har
├── go.mod
└── README.md

License

MIT