jless

jless is a terminal-based viewer for exploring JSON and YAML without leaving the command line. It is best for developers investigating API responses, request payloads, and other structured input; readers who need data transformation should choose a query tool instead.

Overview

jless renders JSON with indentation and syntax highlighting, then lets you move through nested data with keyboard commands inspired by Vim. Objects and arrays can be expanded or collapsed, making large responses easier to scan than raw terminal output. Data mode provides a more streamlined presentation, while line mode shows pretty-printed JSON for a fuller structural view.

Input can come from a file or standard input, including newline-delimited JSON, so it fits pipelines and does not require creating an intermediate document. YAML is also supported when the filename indicates it or when you use the --yaml flag. The viewer omits YAML comments and anchors, which is acceptable for inspecting values and structure but unsuitable when those source annotations matter.

Key features

• Navigation: Collapsing and reopening branches keeps deep documents manageable. Vim-style movement favors keyboard-oriented users and may be less comfortable for people expecting a graphical tree.
• Search: Full-text and regular-expression search can find content in unfamiliar or lengthy input. It is an investigation aid, not a replacement for extracting, filtering, or transforming records.
• Paths and clipboard: Commands copy or print the focused value, key, or path, including unescaped string contents. A jq-style path is useful when you want to carry a discovery into a separate jq command, but jless does not execute jq queries itself.
• Input and display modes: Files, standard input, and newline-delimited JSON are covered, with both streamlined data and formatted line views. YAML broadens the formats it can inspect, while the loss of comments and anchors limits source-preserving review.
• Standalone installation: The Rust project can be installed as one binary. Homebrew, MacPorts, Arch Linux, Void Linux, NetBSD, FreeBSD, Cargo, downloadable binaries, and building from source are listed options. Source builds that enable clipboard access on Linux require X11 libraries.

Pricing

There is no paid tier or trial period. The free plan suits individual developers, teams, and organizations that can work within its supported operating systems and want an open-source terminal viewer. Its trade-off is not a quota or seat limit, but the narrow platform coverage and the absence of a configuration file.

Platforms

jless currently supports macOS and Linux. Package-manager and binary options cover common installations, while Rust users can build it from source. Windows and other desktop platforms are not supported, so cross-platform teams may need another viewer or a separate tool on those machines. The project is released under the MIT License and is credited to CodeIsTheEnd.

Who it's for

Choose jless if your work regularly involves inspecting external API responses, debugging request payloads, or tracing values through deeply nested JSON in a terminal. It is particularly suitable for keyboard-driven developers who want search, collapsible structure, and quick copying of paths or values.

Look elsewhere if your priority is querying and transforming data, preserving YAML comments and anchors, configuring a persistent interface, or using Windows. jless helps you understand input; it does not perform jq-style queries.

Pros and cons

Pros

• Free, MIT-licensed software with no paid upgrade barrier.
• Pretty-printing, syntax highlighting, collapse/expand navigation, and regular-expression search make difficult JSON easier to inspect.
• Reads files, standard input, newline-delimited JSON, and YAML.
• Copies or prints values, keys, and paths, including jq-style paths for follow-up commands.
• Available as a standalone Rust binary with several package and download routes.

Cons

• No jq querying or transformation, so analysis must move to another command.
• YAML comments and anchors are not displayed.
• No configuration-file support yet, limiting persistent customization.
• Support is limited to macOS and Linux; Linux source builds need X11 libraries for clipboard access.

Alternatives

jq is the better choice when filtering, querying, or transforming JSON matters more than interactive browsing; it is free, MIT-licensed, and runs on Linux, macOS, Windows, the web, and self-hosted setups.

Dadroit JSON Viewer suits readers who want a graphical, cross-platform viewer and commercial tiers, including non-commercial opening of files up to 50 MB.

gojq is preferable when you want jq-compatible command-line behavior together with a Go library, on Linux, macOS, Windows, or self-hosted systems.

BracketView is an option for a web-oriented workflow with a free tier and limits on uploads, snapshots, AI actions, and webhooks.

gron is worth choosing when you want to make JSON grep-friendly, with no runtime dependencies and binaries for Linux, macOS, Windows, and FreeBSD.

jaq provides another free, MIT-licensed Rust command-line program and library for users who need processing rather than viewing.

jidoujisho is an Android-only free and open-source option.

JSON Crack is a free-forever open-source online tool for visualizing JSON in a browser or extension.

Verdict

jless is a strong free choice for macOS and Linux users who need fast, keyboard-led inspection of JSON or YAML, especially API and payload debugging. Its focused viewer, search, and path-copying workflow are the reasons to choose it; lack of queries, configuration, Windows support, and preservation of YAML annotations are the reasons to look elsewhere.