# jless — Command-Line JSON Viewer with Interactive Navigation

> jless is a Rust-based terminal JSON viewer designed for reading, exploring, and searching through large JSON data with vim-like key bindings and collapsible tree navigation.

## Install

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# jless — Command-Line JSON Viewer with Interactive Navigation

## Quick Use
```bash
# Install
brew install jless       # macOS
cargo install jless      # via Cargo
# View a JSON file
jless data.json
# Pipe from another command
curl -s https://api.example.com/data | jless
```

## Introduction
jless is a terminal-based JSON viewer that renders JSON data as a collapsible tree you can navigate, search, and explore interactively. It fills the gap between piping JSON through jq for extraction and opening files in a text editor for manual inspection.

## What jless Does
- Displays JSON as an interactive, collapsible tree in the terminal
- Supports vim-like key bindings for navigation (j/k/h/l)
- Provides search functionality to locate keys and values
- Handles large JSON files efficiently with lazy rendering
- Supports YAML input in addition to JSON

## Architecture Overview
jless parses input into a tree data structure and renders visible nodes to the terminal using a TUI framework. Navigation moves a cursor through the tree without re-parsing. Collapsed subtrees skip rendering entirely, allowing large documents to remain responsive. The search function walks the tree and highlights matching nodes.

## Self-Hosting & Configuration
- Install via Homebrew, Cargo, or download prebuilt binaries for Linux and macOS
- No configuration file is needed; jless works out of the box
- Pass files as arguments or pipe JSON through stdin
- Use `--mode line` for a flat line-based view instead of the tree
- Supports reading from compressed files when piped through zcat or similar

## Key Features
- Collapsible tree view with expand/collapse on individual nodes
- Vim-style key bindings including gg, G, Ctrl-d, Ctrl-u for fast navigation
- Regex-based search with n/N to jump between matches
- Data mode that shows raw values vs. line mode for source-level view
- Handles deeply nested documents without performance degradation

## Comparison with Similar Tools
- **jq** — Powerful JSON processor for filtering and transforming, not an interactive viewer
- **fx** — Interactive JSON viewer with JavaScript-based filtering, heavier runtime
- **gron** — Flattens JSON to greppable lines, no tree view
- **bat** — Syntax-highlighted file viewer, no JSON-specific navigation or collapse

## FAQ
**Q: Does jless support editing JSON?**
A: No. jless is read-only. Use jq or a text editor to modify JSON data.

**Q: Can jless handle very large files?**
A: Yes. jless uses lazy rendering so only visible nodes are drawn, making it responsive even with multi-megabyte files.

**Q: Does it support YAML?**
A: Yes. jless auto-detects YAML input and renders it as a navigable tree.

**Q: How do I copy a value from jless?**
A: Press y to yank the value at the cursor position to the system clipboard (where supported).

## Sources
- https://github.com/PaulJuliusMartinez/jless
- https://jless.io

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Author: AI Open Source