Markdown Viewer API documentation
A small, fast REST API for everything markdown — render to safe HTML, beautify, analyze structure, and validate. The same engine that powers our editor, exposed as a developer-friendly API with predictable responses and a generous free tier.
These docs cover every endpoint, every error code, authentication, plan quotas, and a live playground so you can try every call against your own account before you write a single line of code.
Start here
Bearer-token auth with revocable, hashed API keys.
Per-plan quotas (free / pro) plus burst protection.
Stable codes, HTTP statuses, and copy-paste handling examples.
Send real requests against your account from the browser.
API endpoints
All endpoints live under /api/v1 and accept JSON bodies. Each one returns the same { data: … } / { error: … } envelope — authenticate with Authorization: Bearer YOUR_KEY.
/api/v1/renderRender markdown
Convert markdown into safe, sanitised HTML.
/api/v1/formatFormat markdown
Beautify and normalise a markdown document.
/api/v1/analyzeAnalyze markdown
Word count, reading time, links, images, structure.
/api/v1/validateValidate markdown
Lint markdown for common issues.
/api/v1/convert/html-to-markdownHTML → Markdown
Convert any HTML snippet into clean CommonMark + GFM.
/api/v1/convert/markdown-to-textMarkdown → Plain text
Strip markdown formatting and return prose.
/api/v1/convert/csv-to-tableCSV → Markdown table
Convert CSV (or TSV) to a GFM pipe table.
/api/v1/convert/table-to-csvMarkdown table → CSV
Extract the first GFM table to CSV/TSV.
/api/v1/convert/json-to-markdownJSON → Markdown
Render JSON as a table or nested list.
/api/v1/extract/outlineExtract outline
Headings with level, slug, and line number.
/api/v1/extract/linksExtract links
Every link with kind + status.
/api/v1/extract/imagesExtract images
Image audit with alt text and source classification.
/api/v1/extract/code-blocksExtract code blocks
Fenced code with language and suggested filename.
/api/v1/extract/tasksExtract tasks
Task-list items with section + progress.
/api/v1/extract/urlsExtract URLs
Deduped URL list with frequency.
/api/v1/extract/frontmatterExtract frontmatter
Parse YAML frontmatter + body.
/api/v1/generate/tocGenerate table of contents
Markdown TOC from headings.
/api/v1/generate/slugsGenerate slugs
Slugify a list of heading titles.
/api/v1/audit/headingsAudit headings
Skipped levels + duplicate H1 detection.
/api/v1/audit/gfmAudit GFM compliance
Single H1, fence langs, link/image hygiene.
/api/v1/audit/readme-scoreREADME health score
0–100 score across 5 weighted sections.
/api/v1/transform/typographyTypography transforms
Smart quotes, em-dashes, ellipsis, NBSP.
/api/v1/transform/redactRedact secrets
Strip emails, IPs, tokens, keys, JWTs, UUIDs.
/api/v1/transform/normalize-listsNormalize list markers
Rewrite `*` / `+` bullets to `-`.
/api/v1/transform/calloutBuild a callout / admonition
GitHub, Docusaurus, MkDocs, Obsidian flavours.
/api/v1/diffDiff markdown
Line-oriented added / removed / unchanged.
/api/v1/reading-timeReading time
WPM + image + code-aware estimate.
/api/v1/split/sectionsSplit into sections
Chunk by every heading or by level.
What you can build with this API
Render user-generated markdown safely
Power comments, docs, wikis, and forum posts. Every HTML response is sanitised with DOMPurify so embedded XSS payloads never reach your users.
Validate markdown in CI
Lint pull requests for heading-level jumps, inconsistent bullets, missing alt text, and trailing whitespace — all from a single REST call.
Process LLM / AI output
Render ChatGPT, Claude, or Gemini responses to HTML before showing them in your product. Run them through the validator to catch malformed structure.
Generate documentation pipelines
Parse source markdown, extract headings for a table of contents, compute reading time, and render to HTML — all from one API. No parser to bundle in your build.
Resources
- Marketing overview — features, pricing, and use cases
- Dashboard — usage charts, API keys, and billing
- Editor — try the same engine in your browser, no key required
- Live playground — send real requests against your account
- OpenAPI 3.1 spec — import into Postman, Insomnia, or your SDK generator
- llms.txt — machine-readable site summary for AI crawlers