inspect-json-cli

inspect-json is a zero-dependency Node.js CLI for filtered pretty-printing of JSON-heavy AI logs.

It is meant for files like:

• LLM request payloads (e.g. OpenAI / OpenRouter chat completions)
• LLM response payloads
• raw request/response artifacts captured from AI tooling
• JSONL logs
• generic JSON files
• JSON in JSON strings

It is not an interactive viewer. It is a terminal renderer that detects common shapes, recursively decodes JSON embedded inside JSON strings, and prints the useful parts first.

Install

npm i -g inspect-json-cli

At a glance

Given a real LLM response whose message.content is a JSON string, inspect-json detects the response shape, decodes the embedded JSON, and shows the useful parts:

$ inspect-json examples/structured-output-response.json
LLM Response
model: nvidia/nemotron-3-nano-omni
system_fingerprint: nvidia/nemotron-3-nano-omni
usage: 195 total / 58 prompt / 137 completion / 101 reasoning

choice[0]
finish: stop
  role: assistant
  content: json object
    {
      "name": "Ada Lovelace",
      "born": 1815,
      "occupation": "mathematician"
    }

More worked examples (basic chat, tool calls) live in examples/.

Requirements

• Node.js 22 or newer (uses built-ins only).

Install Locally

npm run install-local

By default this writes an inspect-json shim to ~/.local/bin.

You can choose a different destination or command name:

npm run install-local -- --dir ./bin --name inspect-json-dev

Global npm install also works:

npm install -g .

Or run directly:

node bin/inspect-json.mjs raw-response.json

Examples

Let the tool auto-detect the strategy:

inspect-json raw-response.json

Force a request lens:

inspect-json --strategy llm_request raw-request.json

Force a response lens:

inspect-json --strategy llm_response raw-response.json

Use stdin:

cat raw-response.json | inspect-json

Include lower-level ids, raw payloads, and extra metadata:

inspect-json --verbose raw-response.json

Disable color:

inspect-json --no-color raw-response.json

Disable JSON-in-JSON decoding:

inspect-json --raw raw-response.json

Options

--strategy <name>  Force a strategy: json, llm_request, llm_response
-v, --verbose      Include lower-level ids, raw payloads, and extra metadata
--raw              Disable JSON-in-JSON decoding and strategy transforms
--color            Force ANSI color
--no-color         Disable ANSI color
-h, --help         Show help

Color is on by default for TTY output. It is disabled automatically when output is not a TTY or when the NO_COLOR environment variable is set.

Concepts

The renderer is intentionally structured around named strategies and transformers.

Strategies decide how to display a document:

• json: generic pretty JSON fallback
• llm_request: model, messages, tools, response format
• llm_response: choices, assistant content, tool calls, usage, errors

Transformers prepare data before rendering:

• json_in_json: recursively parses string values that contain valid JSON

The --raw flag skips transformers entirely, leaving values exactly as parsed.

When no strategy is supplied, inspect-json scores the input and chooses the most specific strategy. You can override that with --strategy.

Output Style

The output is a filtered pretty print, not a graph. It tries to answer:

• What model/provider was used?
• What messages were sent?
• What tools were exposed?
• What tool calls came back?
• What did message.content contain?
• Was embedded JSON returned as a string?
• What token/cost/usage fields were present?

Development

npm test        # run the node:test suite
npm run check   # syntax check + biome lint
npm run format  # apply biome formatting

This project depends only on Node.js built-ins and has no runtime or dev dependencies. Biome is used for formatting and linting and is expected to be available on your PATH (e.g. installed globally).

License

MIT