what-changed

Compare anything. Understand everything. Break nothing.

A universal CLI tool that compares files, folders, configs, documents, APIs, and dependencies—then explains what changed and what could break.

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Why what-changed?

Traditional diff tools show you what is different. what-changed tells you why it matters:

┌─────────────────────────────────────────────────────────────────────────────┐
│ Traditional Diff              │ what-changed                                │
├───────────────────────────────┼─────────────────────────────────────────────┤
│ < host: localhost             │ [X] BREAKING: database.host changed         │
│ > host: prod-db.example.com   │                                             │
│                               │ Impact: Database connection points to prod  │
│                               │ Could break: Local dev environments         │
│                               │ Risk Score: 9/10                            │
└─────────────────────────────────────────────────────────────────────────────┘

Key Features

Feature	Description
Smart Detection	Auto-identifies 25+ file formats
Semantic Diffing	Understands structure, not just text
Risk Scoring	Predicts what might break (0-10 scale)
OCR Support	Extracts text from scanned PDFs & images
Git Integration	Compare commits, branches, and tags
Interactive TUI	Explore changes in a terminal UI
CI/CD Ready	Exit codes for automation pipelines

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Installation

pip install what-changed

Optional Extras

# Full installation with all formats
pip install what-changed[all]

# Individual extras
pip install what-changed[pdf]      # PDF support (PyMuPDF)
pip install what-changed[ocr]      # OCR for scanned docs (Tesseract)
pip install what-changed[openapi]  # OpenAPI/Swagger specs
pip install what-changed[excel]    # Excel spreadsheets
pip install what-changed[image]    # Image comparison
pip install what-changed[sql]      # SQL schema analysis

From Source

git clone https://github.com/aayushadhikari7/what-changed
cd what-changed
pip install -e ".[all]"

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Quick Start

# Compare any two files
what-changed compare old.json new.json

# Compare directories
what-changed compare ./v1 ./v2

# Show only breaking changes
what-changed compare config.yaml config.prod.yaml --breaking-only

# Interactive graph view
what-changed compare api-v1.yaml api-v2.yaml --graph

# Visual stats dashboard
what-changed compare before/ after/ --stats

# Git integration
what-changed git HEAD~1..HEAD
what-changed git main..feature-branch

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Supported Formats

Configuration Files

Format	Extensions	What's Analyzed
JSON	.json	Keys, values, nested structures
YAML	.yaml, .yml	Full YAML including anchors
TOML	.toml	Sections, tables, arrays
INI	.ini, .cfg	Sections and key-value pairs
ENV	.env, .env.*	Environment variables

Documents

Format	Extensions	What's Analyzed
PDF	.pdf	Pages, text, TOC, metadata, OCR for scanned docs
Markdown	.md	Headings, links, code blocks, sections
Plain Text	.txt	Line-by-line diff

API Specifications

Format	Extensions	What's Analyzed
OpenAPI 3.x	.yaml, .json	Endpoints, schemas, parameters, responses
Swagger 2.0	.yaml, .json	Full spec comparison

Data Files

Format	Extensions	What's Analyzed
CSV	.csv	Schema, columns, rows, statistics
TSV	.tsv	Tab-separated values
Excel	.xlsx, .xls	Multiple sheets, cells

Infrastructure

Format	Files	What's Analyzed
Dockerfile	Dockerfile	Base image, instructions, ports, health checks
Docker Compose	compose.yaml	Services, volumes, networks
SQL	.sql	Tables, columns, indexes, constraints

Dependencies

Ecosystem	Files	What's Analyzed
Node.js	package.json	Dependencies, scripts, versions
Python	requirements.txt, pyproject.toml	Packages, version constraints
Ruby	Gemfile	Gems, sources
Rust	Cargo.toml	Crates, features
Go	go.mod	Modules, versions

Media & Archives

Format	Extensions	What's Analyzed
Images	.png, .jpg, .gif, .webp	Dimensions, metadata, OCR text extraction
Archives	.zip, .tar, .tar.gz	File listing, content changes

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Output Modes

Human-Readable (Default)

what-changed compare config.old.json config.new.json

┌─────────────────────────────────────────────────────────────────────────────┐
│ Configuration Comparison                                                    │
│   A: config.old.json                                                        │
│   B: config.new.json                                                        │
└─────────────────────────────────────────────────────────────────────────────┘

[X] 1 breaking  [!] 2 risky  [o] 3 safe

┌─────────── Changes ───────────┐
│ config                        │
│ ├── database (2 changes)      │
│ │   ├── - host <str>          │
│ │   │     localhost           │
│ │   │     -> prod-db.com      │
│ │   └── ~ port <int>          │
│ │         5432 -> 5433        │
│ └── + cache (3 changes)       │
│     └── enabled = true        │
└───────────────────────────────┘

Interactive Graph TUI

what-changed compare api-v1.yaml api-v2.yaml --graph

Navigate changes with keyboard shortcuts:

• j/k or arrows: Navigate
• Enter: Expand/collapse
• b: Show breaking only
• q: Quit

Visual Stats Dashboard

what-changed compare before/ after/ --stats

Shows ASCII charts with change distribution, risk breakdown, and file type statistics.

JSON Output

what-changed compare config.json config.prod.json --json

Summary Mode

what-changed compare src/ dist/ --summary

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Git Integration

Compare any git references directly:

# Compare with previous commit
what-changed git HEAD~1..HEAD

# Compare branches
what-changed git main..feature-branch

# Compare tags
what-changed git v1.0.0..v2.0.0

# Compare specific file across commits
what-changed git HEAD~5..HEAD -p src/config.json

# Show only breaking changes
what-changed git main..develop --breaking-only

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OCR Support

Scanned PDFs

Automatically extracts text from scanned PDF documents using Tesseract OCR:

what-changed compare scanned_v1.pdf scanned_v2.pdf

┌─────────────────────────────────────────────────────────────────────────────┐
│ PDF Document Comparison                                                     │
│   A: scanned_v1.pdf (OCR detected)                                          │
│   B: scanned_v2.pdf (OCR detected)                                          │
└─────────────────────────────────────────────────────────────────────────────┘

┌────────────────────────────────── page_1  ──────────────────────────────────┐
│ -Invoice #12345                                                             │
│ +Invoice #12345 - REVISED                                                   │
│ -Total: $450                                                                │
│ +Total: $550                                                                │
└─────────────────────────────────────────────────────────────────────────────┘

Images with Text

Compare images and extract text changes:

what-changed compare screenshot_old.png screenshot_new.png

Requirements: Install Tesseract OCR for your platform.

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Risk Scoring

Changes are scored 0-10 based on potential impact:

Score	Level	Examples
8-10	BREAKING	Removed endpoints, deleted dependencies, schema type changes
5-7	RISKY	Major version bumps, config value changes, deprecated features
0-4	SAFE	Added optional fields, new dependencies, comment changes

Common Risk Patterns

Change Pattern	Score	Why
API endpoint removed	10	Clients will fail
Required field added	9	Existing data won't validate
Database host changed	9	Connection failures
Dependency removed	9	Runtime errors
Major version bump	7	Breaking API changes
Port number changed	6	Connection issues
New optional field	2	Backward compatible
Comment updated	1	No runtime impact

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Exit Codes

Perfect for CI/CD pipelines:

Code	Meaning	Action
0	All changes safe	Deploy freely
1	Risky changes found	Review recommended
2	Breaking changes found	Block deployment
3	Error occurred	Check logs

# In CI/CD pipeline
what-changed compare staging.env production.env --breaking-only
if [ $? -eq 2 ]; then
  echo "Breaking changes detected! Blocking deployment."
  exit 1
fi

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CLI Reference

what-changed compare [OPTIONS] SOURCE_A SOURCE_B

Arguments:
  SOURCE_A    First source (file, directory, or URL)
  SOURCE_B    Second source (file, directory, or URL)

Options:
  -s, --summary        Brief summary only
  -b, --breaking-only  Show only breaking changes
  -j, --json           Output as JSON
  -v, --verbose        Show rule matches and scores
  --no-color           Disable colors
  --graph              Interactive TUI graph view
  --stats              Visual statistics dashboard
  --help               Show help message

what-changed git [OPTIONS] REF_SPEC

Arguments:
  REF_SPEC    Git reference (e.g., HEAD~1..HEAD, main..feature)

Options:
  -p, --path PATH      Compare specific file only
  -b, --breaking-only  Show only breaking changes
  --help               Show help message

what-changed detect FILE

  Detect and display the file type.

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Programmatic Usage

from what_changed import compare

# Simple comparison
result = compare("old.json", "new.json")

print(f"Breaking changes: {result.breaking_count}")
print(f"Risky changes: {result.risky_count}")
print(f"Safe changes: {result.safe_count}")

for change in result.breaking_changes:
    print(f"  - {change.path}: {change.summary}")

Advanced Usage

from what_changed.normalize import create_default_registry
from what_changed.diff import SemanticDiff
from what_changed.graph import GraphBuilder
from what_changed.rules import create_default_engine
from what_changed.explain import Explainer

# Full pipeline
registry = create_default_registry()
obj_a = registry.normalize("config.old.json")
obj_b = registry.normalize("config.new.json")

differ = SemanticDiff()
diff_result = differ.diff(obj_a, obj_b)

builder = GraphBuilder()
graph = builder.build(diff_result)

engine = create_default_engine()
rule_results = engine.apply(graph)

explainer = Explainer()
for exp in explainer.explain_graph(graph, rule_results):
    print(f"{exp.risk_level.name}: {exp.change_summary}")

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Edge Case Handling

what-changed handles edge cases gracefully:

Scenario	Behavior
Password-protected PDF	Clear error message
Malformed JSON/YAML	Parse error with line number
Empty files	Shows structure changes
Binary files	Falls back to size comparison
Missing files	Clear "not found" error
Identical files	"No changes detected"
100+ page PDFs	Paginated output (20 items max)
Unicode/Emoji content	Full UTF-8 support
Files without extension	Attempts content-based detection

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Architecture

what-changed/
├── cli/              # Command-line interface (Typer)
├── detect/           # File type detection
├── normalize/        # Format-specific parsers
│   ├── config.py     # JSON, YAML, TOML, INI, ENV
│   ├── pdf.py        # PDF with OCR support
│   ├── openapi.py    # OpenAPI/Swagger
│   ├── data.py       # CSV, Excel
│   ├── docker.py     # Dockerfile, Compose
│   ├── dependencies.py # package.json, requirements.txt
│   ├── image.py      # Images with OCR
│   ├── sql.py        # SQL schemas
│   └── archive.py    # ZIP, TAR
├── diff/             # Semantic diff engine
├── graph/            # Change graph construction
├── rules/            # Risk scoring heuristics
├── explain/          # Human-readable explanations
├── output/           # Renderers (terminal, JSON)
│   └── formats/      # Format-specific renderers
├── tui/              # Interactive terminal UI
└── git/              # Git integration

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Philosophy

• Clarity over cleverness — Readable, maintainable code
• Extensible by design — Easy to add formats and rules
• Deterministic results — No ML/AI, fully reproducible
• Offline-first — No external API calls
• Cross-platform — Windows, macOS, Linux

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Contributing

# Clone and install
git clone https://github.com/aayushadhikari7/what-changed
cd what-changed
pip install -e ".[dev,all]"

# Run tests
pytest

# Type checking
mypy what_changed

# Linting
ruff check what_changed

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License

MIT License — see LICENSE for details.

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_{Built with care for developers who hate surprises in production.
Demo recorded with termgif}