jv

A native desktop JSON viewer with intelligent schema inference, cross-file comparison, and code generation.

Built with Rust and egui for native performance — no Electron, no web runtime. Themed with Catppuccin Mocha.

Features

Four Modes

• Jv — Browse individual JSON files with a tree view, table view, and jq filter execution
• Schema — Interactive entity relationship diagram showing inferred structs and their connections across files
• Groups — Miller-column view grouping common structures and strings across loaded files
• Code — Auto-generated Rust and Swift struct definitions with proper serde/Codable attributes

Smart Schema Inference

• Detects shared data structures across multiple JSON files using Jaccard similarity on field sets
• Merges similar structs with configurable threshold (default 80%)
• Depluralization and singularization for struct naming
• Handles optional fields, mixed types, and nested objects

File Support

• JSON files
• HAR (HTTP Archive) files with automatic response body extraction
• Batch directory import
• Toggle individual source files on/off to dynamically rebuild schema

Performance Focused

• egui's immediate mode rendering keeps the UI snappy even with large JSON files
• Virtual scrolling for long lists — only visible rows are rendered
• Content-based caching with hash keys to avoid redundant recomputation
• No garbage collector, no runtime overhead — just Rust

Session Based

• Create multiple independent sessions, each with their own set of loaded files and configuration
• Sessions persist across app restarts — reopen and pick up where you left off
• Switch between sessions to compare different datasets side by side

Rich Data Handling

• Automatic temporal type detection (ISO 8601 dates, times, Unix timestamps)
• Timezone-aware formatting with relative time display
• Enum variant consolidation from string fields

Build

Requires Rust nightly:

cargo build --release

Run

cargo run

Or after building:

./target/release/jv

Private Tests

Tests in tests/private/ are gitignored so contributors can write tests against their own JSON/HAR data without risking exposing personal or proprietary information to the repository. The test files are included into the main test suite via include!() macros — they compile and run locally but never get committed.

To use private tests, add .json or .har files to samples/private/ and write test functions in tests/private/. Both directories are gitignored.

Dependencies

Crate	Purpose
eframe / egui 0.31	Native desktop UI framework
egui_extras	Syntax highlighting, images, SVGs
egui-phosphor	Icon font
serde_json	JSON parsing
jaq-*	jq query language execution
chrono / chrono-tz	Temporal types with timezone support
rfd	Native file dialogs
walkdir	Directory traversal

License

MIT