
iLovePDF
TinyPNG
Smallpdf
PDF24
ToolKnit
Online Convert
AlionTechStudio Tools
130+ free file tools that run entirely in your browser. No upload, no account.

The modern platform for creating, sharing, and collaborating on AI prompts. Advanced version control and real-time testing.

Which is more popular?
Based on our record, Sunasty seems to be more popular. It has been mentioned 1 time since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | sunasty.com | diffyn.com |
| Pricing | — | |
| Platforms | ||
| Company | Startup from France · 1 - 9 employees · 2026 | — |
| Listed in |
In their own words, as submitted to SaaSHub.


Sunasty is a suite of 130+ free utilities for everyday file tasks: PDF (merge, split, compress, sign, unlock), images (compress, resize, crop, redact, HEIC to JPG), video and audio (compress, convert, trim, extract audio, screen recording), plus developer, date and calculator tools. The...
No description of Diffyn yet.
What each product offers, as listed by its team.


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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The Ultimate Prompt Tool for Creators – Visualize & Organize with Diffyn
How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing Sunasty and Diffyn.
Sunasty's answer
The privacy is structural, not a policy promise: every tool runs entirely in your browser through WebAssembly, so your files never leave your device. You can verify it yourself by opening the DevTools network tab while using any tool: no request carries your file, and everything keeps working offline once the page has loaded. Combined with 140+ tools, no account, no quotas and 28 languages, that architecture is the product.
Diffyn's answer:
Addresses workflow and change management on LLM prompts, provide teams with traceability and visualization of tests across multiple models, provide deeper understading into efficiency of these prompts.
Sunasty's answer
Most popular alternatives (iLovePDF, Smallpdf, CloudConvert, TinyPNG) process files on their servers and monetize through limits: daily quotas, file size caps, subscriptions. With Sunasty there is no upload wait, no copy of your document on someone else's machine, and no counter to unlock, because the work happens on your own hardware. And when a competitor genuinely is the better choice (for example server-side conversion of PDF to editable Word, which a browser cannot do faithfully), our comparison pages say so.
Diffyn's answer:
Diffyn is the platform that specializes on both change management and multi-model analysis.
Sunasty's answer
The site is statically generated with Astro and TypeScript, with lightweight Preact islands for interactivity. The heavy lifting runs client-side in Web Workers through WebAssembly builds of proven engines: FFmpeg for video and audio, qpdf and pdf-lib for PDF, the Squoosh codecs (MozJPEG, OxiPNG, WebP, AVIF) for images, and Tesseract for OCR. There is no application backend at all: the server only delivers static files.
Diffyn's answer:
React, Next.js, POSTGRESQL
Sunasty's answer
Anyone who handles files day to day: people compressing a PDF to fit an application portal or an email cap, gamers and creators trimming and shrinking clips for Discord, anyone blurring a name on a screenshot before sharing it, developers formatting JSON or testing regexes, and privacy-conscious users working with contracts, IDs or anything confidential that should never transit through a third-party server.
Diffyn's answer:
Professionals incorporating LLMs or AI tools in their workflow and wants to keep track of changes and test their prompts.
Sunasty's answer
Sunasty is built by a solo developer in France. The trigger was a familiar frustration: every "free" online tool for a 30-second file task wanted an upload to an unknown server, an account, or a subscription to lift an artificial limit. Modern browsers can do that work themselves thanks to WebAssembly, so Sunasty was built the other way around: the file never leaves your device, by architecture. The amber cat in the logo is the developer's actual cat.
Diffyn's answer:
I started working on Diffyn when I notice that prompting has become an essential part of work across many industries. While there are version control platofrms like github, they are not designed for just prompt management are can be overkill such applications, it is also not integrated natively with various LLMs and relevant tools for users to validate ideas and visualise results properly.
Sunasty's answer
Sunasty is a free consumer tool, so there are no enterprise contracts to name, and since there are no accounts and files never reach us, we genuinely cannot tell who uses it. It is used by individuals worldwide in 28 languages, which is exactly how a privacy tool should work.
Share your experience with using Sunasty and Diffyn. For example, how are they different and which one is better?
Recommendations tracked on public social media and blogs since March 2021.


Have you checked out https://sunasty.com. - Source: Hacker News / 4 months ago
Tracking Diffyn since Jun 2025.
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