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JSON OS

jsonos.online

Free plan Web
Visit jsonos.online
Spec score 7.7 #16 of 29 in JSON Tools

What it is

JSON OS is a free, browser-based workbench that pairs a JSON editor with Markdown Studio, a Markdown previewer. The maker says it needs no signup and that processing runs locally in a Web Worker, with data stored in IndexedDB and nothing leaving the device. The JSON workspace supports up to three panes and can open or accept dropped files. Data can be viewed and edited as a tree, text or table, with table columns switched independently. The editor formats, beautifies, minifies and sorts JSON keys, validates against JSON Schema with Ajv format checks, and repairs malformed input such as smart quotes, comments and unclosed brackets. It compares two documents side by side and supports MongoDB-style filters; JSON arrays can be exported to CSV with a UTF-8 BOM. Markdown Studio supports GitHub-Flavored Markdown, Mermaid, KaTeX, highlighted code and embeds from services including YouTube, Vimeo and GitHub Gist. It sanitizes rendered HTML through DOMPurify, stripping scripts and untrusted iframes. Markdown can be exported as source, copied as rendered HTML or downloaded as standalone HTML.

Spec sheet

Product
JSON OS is a free, browser-based workbench with a JSON editor and Markdown previewer; the maker says it requires no signup.Read 8 Oct 2026 · jsonos.online
Compare and query
The editor compares two documents side by side and supports MongoDB-style filters for querying JSON.Read 8 Oct 2026 · jsonos.online
CSV export
JSON arrays can be exported to CSV with a UTF-8 BOM for Excel compatibility.Read 8 Oct 2026 · jsonos.online
Embed integrations
Markdown URL embeds include YouTube, Vimeo, CodePen, CodeSandbox, JSFiddle, GitHub Gist, and Twitter/X.Read 8 Oct 2026 · jsonos.online
Embeds
Markdown URL embeds include YouTube, Vimeo, CodePen, CodeSandbox, JSFiddle, GitHub Gist, and Twitter/X.Read 8 Oct 2026 · jsonos.online
Exports
JSON arrays can be exported to CSV, and Markdown can be exported as source, copied as rendered HTML, or downloaded as standalone HTML.Read 8 Oct 2026 · jsonos.online
File use
Users can open or drop JSON and Markdown files, and the Markdown Studio can import .md files by drag and drop.Read 8 Oct 2026 · jsonos.online
Formatting
The editor can format, beautify, minify, and sort JSON keys.Read 8 Oct 2026 · jsonos.online
JSON editing
The JSON editor supports tree, text, and table views, plus formatting, minifying, and sorting keys.Read 8 Oct 2026 · jsonos.online
JSON views
The JSON editor can display and edit data in tree, text, or table view, with columns switchable independently.Read 8 Oct 2026 · jsonos.online
Local processing
The maker says processing runs locally in a Web Worker, data is persisted in IndexedDB, and nothing leaves the device.Read 8 Oct 2026 · jsonos.online
Markdown exports
Markdown Studio can export Markdown source, copy rendered HTML, or download a standalone HTML file.Read 8 Oct 2026 · jsonos.online
Markdown features
Markdown Studio supports GitHub-Flavored Markdown, Mermaid diagrams, KaTeX math, syntax-highlighted code, and embeds.Read 8 Oct 2026 · jsonos.online
Markdown safety
The maker says rendered HTML is sanitized with DOMPurify and scripts and untrusted iframes are stripped.Read 8 Oct 2026 · jsonos.online
Output sanitization
Rendered Markdown HTML is processed through DOMPurify, and scripts and untrusted iframes are stripped.Read 8 Oct 2026 · jsonos.online
Privacy and signup
The site says the app requires no signup, uploads, or server processing.Read 8 Oct 2026 · jsonos.online
Query and compare
It supports MongoDB-style JSON filters and side-by-side document comparison with sync-scroll and ignore rules.Read 8 Oct 2026 · jsonos.online
Repair
The editor repairs malformed JSON including smart quotes, trailing commas, unquoted keys, comments, and unclosed brackets.Read 8 Oct 2026 · jsonos.online
Schema validation
The editor validates JSON against JSON Schema using Ajv with format checks.Read 8 Oct 2026 · jsonos.online
Validation and repair
It validates JSON against JSON Schema and can repair issues including trailing commas, unquoted keys, and unclosed brackets.Read 8 Oct 2026 · jsonos.online
Workspace limit
The JSON workspace supports up to three panes.Read 8 Oct 2026 · jsonos.online

Plans and prices

Free Free Browser-based JSON editor and Markdown previewer Read 8 Oct 2026 · jsonos.online

Every JSON OS plan and price →

Strong points and limits

Strong points

  • Free browser-based editor and Markdown previewer.
  • No signup, uploads or server processing, according to the maker.
  • Repairs several common malformed JSON issues.
  • Supports schema validation, comparison and filters.
  • Markdown exports include source and standalone HTML.

Limits

  • The JSON workspace supports up to three panes.
  • Available on web only.

Who it suits

JSON OS suits people who want browser-based tools for inspecting, repairing and comparing JSON alongside Markdown preview and export. Its local-processing approach may appeal to users who prefer data to stay on their device.

Verdict

JSON OS puts JSON editing, validation and comparison alongside a feature-rich Markdown previewer. The three-pane workspace limit and web-only availability are worth weighing against its broad set of browser-based tools.

Where Specifiction places it

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