Incomplete JSON Pretty Printer

Formats JSON that is cut off or malformed, adding indentation as you type and reporting validation state.

Artifact by Simon Willison

IndexedApache-2.0Developer toolsNo sign-up

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Opens tools.simonwillison.net in a new tab. Nothing to install.

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You provide: Broken or partial JSON
You get: Indented JSON
Account: No sign-up needed
AI: No AI: a plain tool
Your input: Not stated: check the tool's privacy notes before using private data
Price: Free to use
Made with: AI-built app
Source: Open source
Link check: Answered on Nov 1, 2026

About

Incomplete JSON Pretty Printer is an AI-built single-page app in the developer tools category (json formatter). It opens in your browser, so there is nothing to install. You provide broken or partial JSON and get indented JSON. It needs no account. It is a plain tool: no AI model is involved. The source code is public on GitHub (simonw/tools).

Category: Developer tools · json formatter

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Details

Auth: No auth
License: Apache-2.0
Repository: github.com/simonw/tools
Website: tools.simonwillison.net/incomplete-json-printer
First seen: Oct 31, 2026
Last checked: Nov 1, 2026
Source: GitHub

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Cite this page

Incomplete JSON Pretty Printer: free online tool. Agent Mart. https://agentmart.dev/artifacts/incomplete-json-pretty-printer (last updated 2026-11-01)