jaq

jaq is a free jq-style processor for command-line users and Rust developers working with structured data. It is best suited to pipelines that need more than JSON or applications that embed jq programs. Its breadth is compelling, but workloads involving untrusted inputs or filters need external resource limits.

Overview

jaq is an open-source jq clone that prioritizes correctness, speed, and simplicity. It pairs a command-line replacement for jq with a Rust library for compiling and running jq programs, making it relevant both to shell-based data work and Rust applications.

That combination is a practical distinction: users can apply familiar jq-style transformations at the command line, while Rust developers can build the same kind of processing into their software. The project describes jaq as memory-safe, and says neither input data nor filters can initiate I/O, though filters may read files before execution.

Key features

jaq works with JSON, YAML, CBOR, TOML, XML, CSV, and TSV. It can transform data with a jq filter while converting between supported formats, reducing the need to split format conversion and querying into separate steps. This makes it a strong fit for developers handling varied structured-data pipelines; it is less compelling for someone who only needs a graphical JSON viewer.

The jaq-core library supports multithreaded use and data types beyond JSON. jaq also permits arbitrary values as object keys and can process strings containing arbitrary bytes, including invalid UTF-8. Those capabilities matter when application data does not fit ordinary JSON assumptions.

The project publishes benchmarks against jq and gojq and reports that jaq is faster on many of them. That gives performance-conscious users a reason to evaluate it, but does not establish that it will be faster for every workload.

One important limit offsets those strengths: jaq does not guard against resource exhaustion. A filter or input can consume unlimited time, memory, or stack space, so jaq should not process untrusted workloads without safeguards imposed elsewhere. The project says Radically Open Security audited jaq's core in two NLnet-funded audits and that all reported issues were addressed; this does not remove the resource-exhaustion risk.

Binary downloads are provided for Linux, Mac, and Windows, with installation instructions for Homebrew and Cargo. An online playground offers a way to try jaq before using it in a local workflow.

Pricing

jaq is free: the jaq plan costs nothing and includes the MIT-licensed open-source command-line program and Rust library. There is no trial to weigh against a paid tier. This is a straightforward fit for individual developers and teams that can use open-source software; there are no paid plans or seat and quota terms to compare.

Platforms

jaq supports Linux, macOS, Windows, API, and self-hosted use. Its CLI and Rust library suit local and integrated development workflows, while binary downloads and Homebrew or Cargo installation options cover common setup paths.

Who it's for

Choose jaq if you already use jq-style filters and need to process or convert formats beyond JSON, or if you want jq-program execution inside a Rust application. Its broader value handling and multithreaded library support are especially relevant to developers with nonstandard data types. Avoid relying on it alone for untrusted inputs or filters: the absence of resource limits is a material operational risk.

Pros and cons

• Pros: One jq-style workflow covers seven formats and can transform data during conversion, useful for multi-format pipelines.
• Pros: The Rust library supports multithreaded use and non-JSON data types, extending jaq beyond a standalone CLI.
• Pros: Free, MIT-licensed software is available for Linux, macOS, and Windows, with Homebrew and Cargo installation paths.
• Cons: No protection against resource exhaustion means untrusted inputs or filters can use unlimited time, memory, or stack space.
• Cons: Its CLI and library focus make it a poor substitute for a visual JSON editor or viewer.

Alternatives

JSON Tools is the broader category for comparing software in this area.

• jq is the direct alternative for readers who want the free, MIT-licensed jq tool and do not need jaq's additional format coverage or Rust library.
• Dadroit JSON Viewer is a better fit for non-commercial users who want to open JSON files up to 50 MB and convert JSON to CSV or XML; its Standard plan costs $98 per y.
• BracketView is an option for readers seeking a browser-based JSON workflow with a free plan that includes uploads up to 5 MB, five encrypted snapshots per month with 10-minute expiry, 20 AI actions per month, and three webhook endpoints with 25 requests each and a two-day term.
• jless is a free, MIT-licensed command-line option for macOS and Linux users who want a narrower JSON-oriented alternative.
• jidoujisho is a free, open-source choice for Android 7.0 and later.
• JSON OS is a free browser-based JSON editor and Markdown previewer.
• JSONBuddy offers a free personal and educational single-user perpetual license with free minor updates and Standard-like functionality; choose it if that license scope and its Windows, API, or extension platforms fit better.
• jsonfmt.dev is an alternative for API users: its free API-key plan allows 100 requests per minute and 1,000 per month across all endpoints, with email support.

Verdict

jaq is an easy recommendation for developers who want jq-style transformation across several data formats or need to embed jq programs in Rust. Its free license, library, and broader value support give it a clear role beyond a basic jq replacement. Look elsewhere, or add strict external limits, when untrusted data or filters could exhaust resources.