Welcome to JSON Schema

September 11, 2025 · View on GitHub

JSON Schema is a vocabulary that allows you to validate, annotate, and manipulate JSON documents.

This repository contains the sources for the work in progress of the next set of JSON Schema IETF Internet Draft (I-D) documents. For the latest released I-Ds, please see the Specification page on the website.

Call for contributions and feedback

Reviews, comments and suggestions are most welcome! Please read our guidelines for contributing.

Status

For the current status of issues and pull requests, please see the following labels

Labels are assigned based on Sensible Github Labels.

Authoring and Building

Specification

To build all the spec files to HTML from the Markdown sources, run npm run build -- specs. You can also build each individually with npm run build -- specs/filename.md (Example: npm run build -- specs/jsonschema-core.md). You can also use wildcards to build multiple specs at the same time: npm run build -- specs/jsonschema-*.md. The HTML files will be available in the web folder.

The spec is built using Remark, a markdown engine with good support for plugins and lots of existing plugins we can use. Remark also has a language server and a VSCode extension we can use to get linting an link checking while developing the spec.

Plugins

The following is a not-necessarily-complete list of configured plugins and the features they make available to you.

remark-lint -- Enforce markdown styles guide.
remark-validate-links -- Check for broken links.
remark-gfm -- Adds support for Github Flavored Markdown specific markdown features such as autolink literals, footnotes, strikethrough, tables, and tasklists.
remark-heading-id -- Adds support for {#my-anchor} syntax to add an id to an element so it can be referenced using URI fragment syntax.
remark-headings -- A collection of enhancements for headings.
- Adds hierarchical section numbers to headings.
  - Use the %appendix% prefix on headings that should be numbered as an appendix.
- Adds id anchors to headers that don't have one
  - Example: #section-2-13
  - Example: #appendix-a
- Makes the heading a link utilizing its anchor

remark-reference-links -- Adds new syntax for referencing a section of the spec using the section number as the link text.

Example:

## Foo {#foo}
## Bar
This is covered in {{foo}} // --> Renders to "This is covered in [Section 2.3](#foo)"
- Link text will use "Section" or "Appendix" as needed

remark-table-of-contents -- Adds a table of contents in a section with a header called "Table of Contents".
remark-code-titles -- Add titles to code blocks
- Example:
```
\`\`\`jsonschema "My Fun Title"
{ "type": "string" }
\`\`\`
```
- The languages jsonschema and json have special styling
- The title will be parsed as a JSON string, but you have to double escape escaped characters. So, to get My "quoted" title, you would need to be "My \\\\"quoted\\\\" title".
rehype-highlight -- Syntax highlighting.
rehype-highlight-code-lines -- Adds line numbers to code blocks. Supports ranges.
remark-flexible-containers -- Add a callout box using the following syntax. Supported container types are warning, note, and experimental.
```
::: {type} {title}
{content}
:::
```