PasteView - Markdown & JSON

Paste and preview Markdown or format, validate and explore JSON. Local drafts, diagrams, math and full-tab editing.

PasteView is a local-first Markdown and JSON workbench that opens in its own full browser tab. Paste or drop in your content and get an instant, cleanly rendered preview or a formatted, validated JSON view — no account, no upload, no server involved. WHY INSTALL - Everything stays on your machine. Documents live only in the page's memory and are cleared when you refresh or close the tab. Nothing is uploaded; no remote scripts or fonts are loaded. - Two everyday formats in one tool. Switch between Markdown and JSON at the top; each keeps its own content and file name. - A real editor, not a text box: line numbers, word wrap, Tab indent, undo, edit / split / preview-only layouts, light and dark themes, and a heading outline with optional synchronized scrolling. MARKDOWN - Paste Markdown or select / drag in .md, .markdown, .mdown and .txt files (up to 10 MB, never truncated). - Tables, task lists, strikethrough, and syntax-highlighted code blocks with one-click copy. - Math via KaTeX: $...$, $$...$$, \(...\), \[...\] and math / latex code blocks. - Diagrams via Mermaid; parse errors are shown inline while your source stays intact. - Download the original Markdown or save a PDF through the browser print dialog. JSON - Paste JSON, import .json files (the tool switches automatically), or paste a JSON code fence. - Format, minify, re-indent with 2 or 4 spaces, copy and download; unwrap escaped strings that contain valid JSON. - Explore with a collapsible tree: expand / collapse all, search keys and values; long trees load in batches without truncating exports. - Read-only formatted preview with line numbers and paired fold arrows for objects and arrays. - Honest validation: errors point to the exact line and column and jump to the editor. Long integers, original number formatting, field order and duplicate keys are preserved — no silent "fixing", and ordinary prose is never guessed as JSON. PRIVACY & PERMISSIONS - The only permission is clipboardRead, used solely when you click "Paste content". The clipboard is never monitored or read automatically; you can always paste manually into the editor. - Raw HTML in Markdown is displayed as text, and generated HTML is sanitized with DOMPurify. External images are off by default and load only if you enable them in reading settings. - Interface in English and Simplified Chinese, following your browser language and switchable in reading settings. Paste once, see it rendered. Install PasteView for the notes, drafts, API responses and config files you handle every day.