The SynthQuery Free Online Markdown Editor and Live Preview is a privacy-first workspace for writing, refactoring, and reviewing Markdown in the browser. You edit CommonMark-style source in a full-featured CodeMirror surface with syntax-aware highlighting, optional line wrapping, and quick-insert snippets for headings, lists, links, and fenced code blocks, while a rendered pane shows GitHub Flavored Markdown output—including tables, task lists, strikethrough, and autolinks—without sending your draft to our servers. Autosave keeps progress in local storage, Open and Download handle real .md files, and split or single-pane layouts adapt to laptops, ultrawide monitors, and tablets. The tool belongs to SynthQuery’s Free tools series alongside the HTML Online Viewer, Lorem Ipsum Generator, Word Counter, Grammar Checker, and Dictionary, and it bridges naturally into AI-assisted workflows when you need readability scoring, tone checks, or originality review after the structure is stable. For the complete product catalog—including detection, humanization, plagiarism scanning, summarization, and translation—use the central hub at https://synthquery.com/tools, which the site footer links to as “All tools.”
What this tool does
At the center of the experience is a dual-pane workflow that mirrors how professional technical writers and developer advocates actually work: keep source truth on the left, validate reader-facing semantics on the right, and iterate without context switching. The editor uses CodeMirror 6 with the Markdown language pack, so emphasis markers, list indentation, fenced languages, and front-matter-like YAML-looking blocks receive predictable highlighting. A formatting strip offers pragmatic shortcuts—insert ATX headings, bullet or numbered lists, block quotes, horizontal rules, inline code, and code fences—so mobile users are not forced to hunt for backtick keys. Power users still get keyboard efficiency: Ctrl or Cmd plus Enter refreshes the preview when live mode is off, matching the muscle memory from the HTML viewer utility.
Live preview debounces as you type to protect battery life on large documents, yet you can disable it when pasting megabyte-scale generated logs or migration files where immediate re-render would spike main-thread work. A table of contents panel scans heading lines in the source, displays a navigable outline with depth-aware indentation, and deep-links into preview headings via stable slug identifiers, which is invaluable for long playbooks, RFC drafts, and onboarding manuals. Statistics in the chrome report words, characters, lines, and estimated reading time using the same heuristics content strategists expect from adjacent utilities, so you can jump to the Word Counter or Grammar Checker only when you need sentence-level critique rather than coarse length.
The preview pipeline runs entirely client-side through react-markdown with remark-gfm, which implements the most common GitHub extensions teams rely on in README files, internal wikis, and product docs. That means pipe tables survive round trips from Notion or GitHub exports, task list checkboxes render for sprint notes, and strikethrough communicates deprecated API paths without hand-authoring HTML. For security, raw HTML passthrough is not enabled in the renderer, reducing cross-site scripting surprises when collaborators paste untrusted snippets—if you must preview mixed HTML, use the dedicated HTML Online Viewer in the Free tools hub, then return here for prose-first authoring.
Productivity details matter at scale: word-wrap toggles for diff-friendly wide lines versus readable narrow columns; three editor font steps reduce eye strain during night edits; copy Markdown to clipboard in one click for Slack or issue comments; download a UTF-8 .md artifact named for attachments; clear resets scratch buffers when practicing syntax. Nothing in this flow uploads your text to SynthQuery compute for rendering—network activity is limited to whatever external images or links you intentionally reference inside the document, same as any local editor opening a preview pane.
Use cases
Engineering teams paste pull request templates, CONTRIBUTING guides, and ADRs to verify heading hierarchy and tables before committing, then follow internal links to the AI Detector or Paraphraser when policy text still needs a compliance pass. Developer relations authors draft release notes with fenced code samples, confirm list nesting, and share downloads with stakeholders who refuse to read raw Markdown in email. Product managers maintain living roadmaps where task lists mirror Jira epics; the outline sidebar becomes an improvised mini sitemap during roadmap reviews.
Marketing and SEO specialists outline long-form articles in Markdown first—because version control diffs stay readable—then use the reading-time estimate to plan hero sections and newsletter slots before moving copy into the CMS. When tone tightness matters, they open the Grammar Checker or SynthRead readability tool in another tab without leaving SynthQuery’s domain. Students and bootcamp learners compare source syntax with rendered output side by side, accelerating intuition for links, images, and emphasis rules more effectively than static cheat sheets.
Journalists and researchers preparing plain-text submissions use the editor to strip vendor-specific formatting, confirm footnote-style paragraphs (as normal text), and export a clean file. Agencies juggling multiple clients rely on local autosave so browser crashes never vaporize billable drafts. Localization coordinators inspect translator-supplied Markdown for broken fences or accidental heading demotions that would skew TOC imports. Whenever the job is “write structured text quickly, preview faithfully, stay local,” this page competes with desktop apps while staying one click away from SynthQuery’s broader intelligence stack.
How SynthQuery compares
Browser Markdown toys range from minimalist textareas with delayed preview to cloud notebooks that persist every keystroke on a vendor server. SynthQuery targets experienced users who want GitHub-flavored fidelity, an IDE-grade editor, honest privacy boundaries, and a direct path to AI verification tools—without forcing account creation for basic editing.
Aspect
SynthQuery
Typical alternatives
Privacy model
Preview and autosave run locally; no Markdown upload for rendering.
Some hosted editors sync drafts to the cloud by default.
Markdown flavor
GFM-oriented tables, task lists, strikethrough, autolinks via remark-gfm.
Strict CommonMark-only pages omit tables or checklists teams expect.
Editor depth
CodeMirror 6 with Markdown highlighting, wrap modes, insert toolbar.
Plain textarea previews offer no structural assistance or folding.
Ecosystem
Same session can extend to Grammar, Word Counter, HTML viewer, /tools hub.
Standalone gadgets lack bridges to detection, readability, or plagiarism.
HTML mixed documents
Raw HTML blocks are not executed here; use the HTML viewer for markup-first files.
Some renderers allow arbitrary HTML, increasing XSS exposure.
How to use this tool effectively
Begin with a clear filename intent—even if you have not saved yet—so Download uses a meaningful default. Choose Split view when you are authoring; switch to Source only if you need maximum horizontal space for tables, then return to Split to validate rendering. Enable Live preview for iterative sentence edits; disable it before bulk-pasting generated content to avoid UI thrash.
Use the outline to jump between H2 sections during restructuring; if headings move, re-scan visually in the preview to confirm anchors still make narrative sense. When inserting samples from the web, strip tracking parameters from URLs and prefer descriptive link text for accessibility. For code blocks, always specify a language token after the opening fence so teammates recognize syntax in both panes.
After drafting, run Copy to grab Markdown for your git repo, or Download to attach the file to a ticket. If downstream systems need rendered HTML, export Markdown from here and transform it in your static site generator—avoid pasting untrusted HTML back into this preview. When prose quality is the remaining risk, open Grammar Checker and SynthRead; when authenticity matters, run the AI Detector or Plagiarism Checker. Bookmark https://synthquery.com/free-tools for sibling utilities and https://synthquery.com/tools for the entire SynthQuery catalog linked from the footer.
Limitations and best practices
This preview is not a full static site generator: it does not resolve custom shortcodes, component imports, or proprietary wiki macros your organization may rely on. Footnote extensions, definition lists, and math typesetting are not enabled—add those in specialized publishing pipelines. Very large documents may hit a character guardrail designed to protect low-memory devices; split monorepo readmes per package when necessary. Remote images in Markdown still trigger browser fetches; do not embed credentials in URLs. Always review collaborator Markdown for phishing links before sharing externally. Pair this utility with institutional style guides; automated tools cannot replace legal review for regulated industries.
The authoritative index at /tools lists every capability—utilities, AI detection, SynthRead readability, plagiarism, humanizer, summarizer, translator, and more—matching the footer “All tools” link to https://synthquery.com/tools.
Browse the curated Free tools series: Markdown editor, HTML viewer, WebP converter, calculators, robots.txt generator, and other zero-quota helpers in one searchable layout.
Soften stilted LLM output in tutorials after structural Markdown is finalized.
Frequently asked questions
No. Editing, syntax highlighting, GitHub-flavored preview rendering, and local autosave all execute inside your browser. SynthQuery does not receive your Markdown body merely because you typed it here, which mirrors how our HTML viewer treats srcDoc previews. If your document references external images or links, the browser may fetch those resources directly from their hosts—exactly as it would in any local editor with a preview pane—so avoid embedding secrets in URLs. Enterprises evaluating data residency should still route sensitive drafts through their approved VPN or air-gapped machines; this page simply removes an unnecessary server round trip for rendering. When you later choose to run Grammar Checker, AI Detector, or Plagiarism Checker, those tools follow their own documented handling for analysis traffic.
The preview targets GitHub Flavored Markdown conventions via remark-gfm: fenced code blocks with optional language hints, tables using pipe syntax, task list items with checkbox markers, strikethrough with paired tildes, and autolinks for bare URLs in many contexts. It aligns with what engineers expect from README files on major git hosts. It is not a complete reimplementation of every vendor extension—wikis that rely on macros, embeds, or custom shortcodes may diverge. For documents that interleave large HTML fragments, use the HTML Online Viewer instead, because raw HTML is intentionally not executed inside this Markdown renderer to reduce XSS risk. When in doubt, test a small snippet in Split view and compare against your production pipeline’s own Markdown processor.
Autosave writes the current editor buffer to localStorage under a versioned key so refreshing the tab or briefly losing connectivity does not erase your session. Clearing site data for synthquery.com removes it; the Clear button inside the tool resets the editor to a starter document and overwrites stored content with that sample. Private browsing modes may discard storage when the window closes—Download important files before ending the session. Autosave is a convenience layer, not version control: for audit trails, commit Markdown to git or copy artifacts into your CMS. Teams collaborating simultaneously should still use a real shared repository rather than expecting multi-cursor sync here.
Yes. Use Open file to choose a .md or .txt document from your device; the contents replace the editor buffer and immediately flow into preview according to your Live preview setting. Large files may approach stability limits documented in the UI; if that happens, split the source into smaller chapters. Download emits UTF-8 Markdown with a sensible default filename you can rename in the save dialog. This workflow pairs well with static site generators: edit here, save, then let Hugo, Eleventy, Astro, or Jekyll handle final HTML emission. Remember that preview fidelity may still differ slightly from your SSG’s plugin stack—always run a local build before shipping.
Long documents benefit from an outline that mirrors ATX headings (# through ######). The sidebar lists them in source order with indentation proportional to depth. Clicking an item scrolls the preview to the corresponding heading, using slugified IDs derived from heading text. If two headings share identical labels, browsers require unique IDs; you should manually differentiate headings in the source to avoid ambiguous anchors. The outline updates as you type, making it a lightweight navigation aid for specs and playbooks. It does not replace PDF bookmarks or CMS navigation trees, but it accelerates peer review sessions conducted entirely in the browser.
Debounced live rendering is ideal for incremental writing, yet pasting thousands of lines—such as build logs or CSV excerpts inside fenced blocks—can spike layout work. Turning live preview off lets you paste, manually invoke refresh with Ctrl or Cmd Enter, and verify rendering once the buffer stabilizes. The same toggle helps low-power laptops when fans spin during heavy edits. You still retain syntax highlighting in the editor regardless. This pattern matches professional IDEs that distinguish “automatic builds” from “manual save” workflows. Re-enable live mode when you return to normal paragraph-scale edits.
The HTML viewer renders documents as a browser page inside a sandboxed iframe, with optional script allowances for trusted testing. This Markdown editor treats Markdown as the source of truth and renders semantic HTML output through a constrained pipeline without arbitrary raw HTML blocks. Use Markdown here for prose, specs, and readme-style content; pivot to the HTML viewer when you must inspect tag structures, marketing email tables, or legacy CMS exports. Many teams draft in Markdown first, then export HTML through their build tooling, previewing intermediate states here. Both utilities live in the Free tools program and link to the central /tools catalog for AI-powered follow-up steps.
Absolute HTTPS image URLs typically render in the preview because the browser can fetch them. Relative paths like ./diagram.png resolve only if the browser can access that path from the current origin context—static previews may not know your filesystem layout, so relative assets might appear broken until you serve the project from a local dev server. For documentation work, prefer absolute URLs to hosted assets or rely on your static site generator to rewrite paths during build. Link text should remain descriptive for screen readers; avoid “click here.” If you need to validate final on-site URLs, use your staging environment after exporting Markdown from this tool.
Start at https://synthquery.com/free-tools for the curated Free tools grid that includes this Markdown editor, the HTML viewer, converters, calculators, and more. When you need the full lineup—AI detection, SynthRead readability, plagiarism scanning, humanization, summarization, translation, chat, and enterprise-facing capabilities—open https://synthquery.com/tools, which is linked from the site footer as “All tools” for consistent discovery across pages. That hub is the single best place to internal-link teammates who ask “what else can SynthQuery do?” after they finish editing Markdown. Pricing and quotas for compute-heavy features remain documented on /pricing.
Rendered headings, lists, links, and tables map to semantic HTML elements, which assists assistive technologies in navigating the preview. The editor itself relies on CodeMirror’s accessibility improvements, but complex Markdown may still require listening to raw source for punctuation cues. Always perform dedicated QA with your organization’s preferred screen reader combinations before claiming WCAG conformance for published pages, because final site templates add chrome this preview cannot simulate. Color contrast of inserted content depends on your Markdown—not on SynthQuery’s chrome—so avoid low-contrast custom HTML hacks; stick to semantic emphasis instead.
Browsers print the visible page; you can focus the preview pane and use the system print dialog to produce a PDF, though stylesheet rules from this tool may differ from your corporate letterhead. For formal PDFs, export Markdown into your usual toolchain (Pandoc, LaTeX, or docs platforms) where margins, headers, and fonts are controlled. SynthQuery does not add a dedicated PDF engine here to keep the utility lightweight and local-first. If you need pixel-perfect WYSIWYG, copy the rendered text structure and apply branded CSS downstream.