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

AgentGatePay
x402
Real-world tasks your agent can't do alone.

Which is more popular?
Based on our record, Underscore Done 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 | diffyn.com | underscoredone.com |
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| Platforms | — | |
| Company | — | Startup from the United States · 2026 |
| Listed in |
In their own words, as submitted to SaaSHub.


No description of Diffyn yet.
Underscore Done (_done) is a suite of pay-per-call utility APIs built for AI agents. No API keys, no subscriptions - agents pay per request with USDC via the x402 protocol
What each product offers, as listed by its team.


No features have been listed yet.
An editorial look at what each product does well and who it suits.


Overall verdict
Why this product is good
Recommended for
No analysis of Underscore Done yet.
Walkthroughs and reviews on video.
The Ultimate Prompt Tool for Creators – Visualize & Organize with Diffyn
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How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing Diffyn and Underscore Done.
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.
Underscore Done's answer:
We provide data and actions that AI cannot achieve.
Also we don't require accounts, registration, api keys. And we charge per usage and never charge monthly subscriptions.
Diffyn's answer
Diffyn is the platform that specializes on both change management and multi-model analysis.
Diffyn's answer
React, Next.js, POSTGRESQL
Diffyn's answer
Professionals incorporating LLMs or AI tools in their workflow and wants to keep track of changes and test their prompts.
Underscore Done's answer:
Ai Agents that work on behalf of people.
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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Recommendations tracked on public social media and blogs since March 2021.


Tracking Diffyn since Jun 2025.
_done is a catalog of small, pay-per-call utility APIs aimed at AI agents: things like DNS and WHOIS lookups, screenshots, OCR, hashing, QR codes, and SEO extraction. Every call costs one cent in USDC over x402. There's no account and no... - Source: dev.to / 11 days ago