Agenta vs Langtail
Both are prompt management tools. Here is how they actually differ on price, billing model and deployment.
Agenta
An MIT-licensed LLMOps platform bundling prompt management, evaluation, human annotation and observability, with a visual playground for side-by-side comparison. Actively shipping, self-hostable, and broader than most open-source competitors.
Langtail
A no-code prompt debugging, testing and deployment platform with an AI Firewall option. Unusually, it meters the number of prompts you can have - 20 on the $99 tier - which is a strange ceiling for a prompt management tool.
| Agenta | Langtail | |
|---|---|---|
| Category | Prompt Management | Prompt Management |
| Our rating | 4/5 | 3/5 |
| Starting price | $0 self-hosted | $99/mo |
| Billing meter | No usage metering | prompt |
| Free plan | Yes | Yes |
| Free self-hosting | Yes, free | No or paid tier only |
| Best for | Teams that want one self-hosted MIT-licensed platform covering prompts, evaluation and observability, and who value environment promotion and branching over best-in-class depth in any single area. | Product teams that want a polished no-code prompt debugging and deployment surface, have a small and stable number of prompts, and value unlimited logging over low cost. |
Our verdict on Agenta
Agenta is the broadest MIT-licensed option in this segment and a sensible default if you want one self-hosted tool rather than three. It covers prompt management, automated evaluation, human annotation and observability, with an interactive playground for side-by-side comparison and support for 50+ providers including self-hosted models. The versioning model is better than most - branching and environment promotion means you can develop a prompt on a branch and promote it through environments rather than just rolling back a linear history, which is closer to how you already ship software. It is actively maintained, with v0.82.0 shipping in February 2026 and roughly 4,200 stars. The trade-off is depth. The evaluation surface is lighter than DeepEval or Ragas and the observability lighter than Langfuse, so a team with a serious requirement in either area will end up pairing it with something. One note on reading their material - Agenta publishes competitor comparisons, and we found their licensing claim about Latitude to be wrong in a way that disadvantages a rival.
Full Agenta review →Our verdict on Langtail
Langtail is a competent, actively maintained platform with one pricing decision that deserves scrutiny. It meters the number of prompts you can have - two on free, twenty on the $99 Pro tier, unlimited only at $499. That is an unusual ceiling for a prompt management tool, because the number of prompts is not a proxy for value received or cost incurred, and it penalises exactly the behaviour the product should encourage. Splitting one overloaded prompt into three focused ones is good practice and here it costs you 15% of your allowance. Most competitors meter requests, logs or seats, all of which at least correlate with usage. Set against that, the product is solid - a no-code interface genuinely aimed at product teams, unlimited logs from Pro upward, and retention scaling to a year on Team. The AI Firewall is an interesting differentiator, though like self-hosting it sits behind Enterprise. At roughly ten times PromptHub's entry price, you are paying for polish and the logging allowance.
Full Langtail review →Frequently Asked Questions
What is the main difference between Agenta and Langtail?
Agenta: Teams that want one self-hosted MIT-licensed platform covering prompts, evaluation and observability, and who value environment promotion and branching over best-in-class depth in any single area. Langtail: Product teams that want a polished no-code prompt debugging and deployment surface, have a small and stable number of prompts, and value unlimited logging over low cost. Both sit in Prompt Management, so the decision usually comes down to billing model and deployment rather than raw capability.
Which is cheaper, Agenta or Langtail?
It depends entirely on your workload shape, because they meter differently - Agenta bills on no usage metering and Langtail bills on prompt. Published starting prices are $0 self-hosted and $99/mo respectively, but those numbers are not comparable until you apply them to the same traffic. Use our cost calculator to model both against your own request volume and span count.
Can I self-host Agenta or Langtail?
Agenta: Yes, free. Langtail: No or paid tier only. Free self-hosting means no licence fee, not no cost - you still own the infrastructure, upgrades and on-call.