
Todo.ly
Todo
Todo.txt
Todo.is
Checklist
checklist.gg
To Do List & Notes
A simple, fast, and private TODO app with sync, recurring tasks, and offline support.

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

Website, pricing, platforms and company facts side by side.
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| Website | todo.73.nu | diffyn.com |
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| Company | Startup from Germany · 2026 | — |
| Listed in |
In their own words, as submitted to SaaSHub.


TODO is a fast, private task manager that runs entirely in your browser. Create one-time, recurring, or date-range tasks with flexible scheduling. From simple daily reminders to biweekly spans with completion targets. Organize tasks into color-coded folders and arrange them in your preferred...
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What each product offers, as listed by its team.


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


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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 TODO.73.nu and Diffyn.
TODO.73.nu's answer
Span mode. Most todo apps force tasks into rigid daily checkboxes or single deadlines. TODO.73.nu lets you define recurring time windows with completion targets. "Exercise 3 times this week" tracks across Monday to Sunday and stops showing up for that time span, after checking it three times. On top of that, optional sync is end-to-end encrypted so the server can't read your tasks. No accounts, no sign-up, just a shared key.
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.
TODO.73.nu's answer
Because it handles scheduling patterns that Todoist, Apple Reminders, and Google Tasks simply can't. "Do this 2 times between Monday and Friday." "Complete this 4 times within this date range." Those tools don't understand flexible windows. Beyond that, it's fast, private, and simple. No tracking, no ads, works offline, loads instantly, and your data stays yours.
Diffyn's answer:
Diffyn is the platform that specializes on both change management and multi-model analysis.
TODO.73.nu's answer
Vanilla HTML, CSS, and JavaScript. No frameworks, no build tools, no dependencies. The whole app is a single HTML file. Encryption runs through the browser's native Web Crypto API (AES-256-GCM, PBKDF2). Service Workers handle offline use and PWA installation. LZ-String compresses data in localStorage. The backend is a small PHP script that only stores encrypted blobs and never sees your actual data. The whole thing is deliberately simple and self-hostable.
Diffyn's answer:
React, Next.js, POSTGRESQL
TODO.73.nu's answer
People who think in time blocks rather than strict daily routines. You want to run three times this week but don't care which days. You need to finish something within a project window and want to see progress without micromanaging individual dates. Privacy matters to you, but you also just want something that works without creating yet another account.
Diffyn's answer:
Professionals incorporating LLMs or AI tools in their workflow and wants to keep track of changes and test their prompts.
TODO.73.nu's answer
I wanted a simple way to track tasks that need to happen a certain number of times within a flexible window. Exercise 3 times this weekend. Finish something 5 times during a two-week stretch. Every app I tried forced per-day schedules. None of them got the concept of "X times within this span." So I built it. Span mode was the reason this app exists. Everything else (encrypted sync, offline support, the minimal design) grew around it because I wanted something I could actually use every day without giving up privacy or dealing with bloat.
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.
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