
JSFiddle
CodeSandbox
GitHub
replit
VS Code
Pastebin.com
JS Bin
A front end web development playground.

Atticus
KDP Builder
Vellum
Reedsy Book Editor
Scrivener
Adobe InDesign
Sudowrite
Web-based book formatting for indie authors. Import Markdown, Word or PDF, choose from 15 typographic templates, export polished epub, print-ready PDF (KDP, IngramSpark) and DOCX. Built-in AI tools, no Mac required.

Which is more popular?
Based on our record, CodePen seems to be more popular. It has been mentioned 513 times since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | codepen.io | foliostudio.app |
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| Company | — | Startup from France · 1 - 9 employees · 2026 |
| Listed in |
In their own words, as submitted to SaaSHub.


No description of CodePen yet.
Folio Studio is a web-based book formatting tool for independent authors. Import your manuscript (Markdown, Word DOCX, ODT or PDF), choose from 15 typographic templates designed for different genres (novel, thriller, romance, essay, academic, illustrated), then export polished epubs, print-ready...
What each product offers, as listed by its team.


Possible disadvantages
An editorial look at what each product does well and who it suits.


Overall verdict
Why this product is good
Recommended for
Overall verdict
Why this product is good
Recommended for
Walkthroughs and reviews on video.
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How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing CodePen and Folio Studio.
Folio Studio's answer:
Folio Studio's answer:
Folio Studio is one of the few book formatting tools designed natively for Markdown writers. Unlike Vellum (Mac-only, $249) or Atticus ($147), it runs entirely in the browser on Windows, Mac and Linux, supports French and English from day one, and combines typographic templates, real-time preview, and built-in AI tools (chapter analysis, rephrasing, cover generation) in a single workflow. Free to start, no credit card required.
Folio Studio's answer:
Three reasons. (1) Cross-platform: it works on any computer with a browser, while Vellum is locked to Mac. (2) Markdown-first import: ideal for authors writing in Obsidian, iA Writer, Typora or VS Code, which Vellum and Atticus don't support natively. (3) Pricing: free plan to publish your first epub without watermark, then €4.99/month Starter or €9/month Pro, vs $147–$399 one-time for desktop alternatives.
Folio Studio's answer:
Independent authors publishing on Amazon KDP, IngramSpark, Apple Books or Kobo who want a clean export pipeline without learning Pandoc or LaTeX. Also students and academics writing memoirs, dissertations or research reports who need print-ready PDFs with proper typography. Mostly Windows and Linux users frustrated by Vellum's Mac-only restriction, plus French-speaking authors underserved by English-only tools.
Folio Studio's answer:
Folio Studio started as a frustration with existing book formatting tools. Vellum is excellent but Mac-only and expensive. Atticus is cross-platform but lacks Markdown import and AI features. Pandoc and Calibre produce technically valid epubs but ignore typography. Folio Studio combines the typographic quality of Vellum, the cross-platform accessibility of Atticus, and the Markdown-first workflow that modern authors expect, into a single web app.
Folio Studio's answer:
Next.js 16 (App Router) for the web application, TypeScript end-to-end, Tailwind CSS v4 for styling, Supabase for authentication, database (PostgreSQL) and file storage, Stripe for billing, Puppeteer for PDF rendering, Replicate (FLUX) for AI cover generation, and the Anthropic Claude API for AI chapter analysis. Deployed on Vercel with Fluid Compute.
Share your experience with using CodePen and Folio Studio. For example, how are they different and which one is better?
External articles and on-site reviews we used to compare the two products.


Codepen is a social network for developers to show off their work, ask and answer questions, and exchange ideas. It's like a Reddit for coding and design, with a large community of talented web developers.
Codepen is a social development environment that allows developers to showcase their work and experiment with HTML, CSS, and JavaScript in a collaborative space. Codepen’s focus on visual and interactive development...
Codepen is a social development environment for front-end designers and developers. Build and deploy a website, show off your work, build test cases to learn.
We have no reviews of Folio Studio yet. Be the first one to post
Recommendations tracked on public social media and blogs since March 2021.


> I vividly remember IE and many hacks to have css elements properly working in it… The common advice now is to only use CSS that is supported in the last two major versions of each major browser. You can check any css property's support... - Source: Hacker News / 2 months ago
Thank you, heartfelt... For sharing an artwork, a miracle! Just in case, have you considered publishing the work at platforms as CodePen, where genius Artists/People express their art, too, as you?: // https://codepen.io/. - Source: Hacker News / 3 months ago
Embed on DEV: If you prefer CodePen embed, create a Pen with that HTML and add to the post as: {% codepen https://codepen.io//pen/ %}. - Source: dev.to / 12 months ago
Tracking Folio Studio since May 2026.
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