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

Helicone AI
LangSmith
LangChain
Portkey
Braintrust.dev
PromptLayer
LastMile AI
Langfuse is an open-source LLM engineering platform that helps teams collaboratively debug, analyze, and iterate on their LLM applications.

Which is more popular?
Based on our record, Langfuse seems to be a lot more popular than Underscore Done. While we know about 35 links to Langfuse, we've tracked only 1 mention of Underscore Done.
Website, pricing, platforms and company facts side by side.
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| Website | underscoredone.com | langfuse.com |
| Pricing | ||
| Company | Startup from the United States · 2026 | Startup from the United States |
| Listed in |
In their own words, as submitted to SaaSHub.


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
Langfuse is an open-source LLM engineering platform designed to empower developers by providing insights into user interactions with their LLM applications. We offer tools that help developers understand usage patterns, diagnose issues, and improve application performance based on real user data....
What each product offers, as listed by its team.


No features have been listed yet.
Possible disadvantages
Walkthroughs and reviews on video.
No Underscore Done videos yet. You could help us improve this page by suggesting one.
Langfuse in two minutes
How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing Underscore Done and Langfuse.
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.
Underscore Done's answer
Ai Agents that work on behalf of people.
Share your experience with using Underscore Done and Langfuse. For example, how are they different and which one is better?
External articles and on-site reviews we used to compare the two products.


We have no reviews of Underscore Done yet. Be the first one to post
Ten free AI prompt tools in 2026 across four categories: prompt generators (SurePrompts, Anthropic Console, OpenAI Playground), libraries (AIPRM, PromptHero, FlowGPT, Awesome ChatGPT Prompts), open-source workflow...
Recommendations tracked on public social media and blogs since March 2021.


_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 / 13 days ago
Langfuse is an open-source LLM engineering platform specialized for AI applications. It provides:. - Source: dev.to / about 8 hours ago
Langfuse is an open-source observability and analytics platform for LLM applications. Its open-source nature is a significant draw for companies that prefer to self-host or want to avoid vendor lock-in. - Source: dev.to / 6 days ago
We have researched and experimented with several AI evaluation platforms, including Arize Phoenix, Microsoft Foundry, and Langfuse. After evaluating them against our requirements and roadmap, we shortlisted Microsoft Foundry and Langfuse... - Source: dev.to / 15 days ago
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