fx

fx is a JSON-first terminal tool with two modes: a fullscreen viewer for browsing documents and a JavaScript-powered processor for transforming data from stdin or files. It can also parse YAML or TOML input and route it through the same workflow.

• Browse nested JSON, search keys or values, collapse sections, preview nodes, and print selected paths or values from a terminal viewer.
• Pipe JSON streams through JavaScript expressions to extract fields, map or filter arrays, slurp multiple objects, or process raw text lines.
• Edit JSON files in place with expression chains and the built-in save function, or ingest YAML and TOML and emit JSON for later steps.

• Expression mode reads stdin or files, writes results to stdout, and returns non-zero exits on parse or JavaScript errors, which suits inspect and transform loops.
• Structured output is native here: object and array results are emitted as pretty JSON, while scalar values print directly for shell composition.
• The fullscreen viewer is useful for human debugging, but unattended agents should usually call explicit expressions and treat the TUI as optional exploration.

• The transformation language is JavaScript-flavored rather than jq syntax, so automation often needs a quick docs or --help pass before first use.
• In-place edits require a real file path and the special save function; that path is unavailable on stdin and symbolic links are refused.