Langfuse vs Langtail

Langfuse

Langfuse is a strong default for teams that want tracing, prompt versioning and evaluations in one open-source tool, with the option to keep data on their own infrastructure. Teams that only want a hosted logging proxy with no SDK work, or that need guaranteed enterprise SSO without paying for add-ons, may find simpler or more bundled options.

Pros

• +MIT-licensed core that can be self-hosted without usage limits
• +Covers tracing, prompt management, evaluation and dashboards in one product
• +Generous free cloud tier and unlimited users from the $29 Core plan
• +OpenTelemetry support and SDKs for Python and JavaScript

Cons

• −Usage above the included 100k units is billed extra, so busy apps pay more than the headline price
• −Free tier keeps only 30 days of data and two users
• −Enterprise SSO and RBAC require the $300 Teams add-on on Pro or the Enterprise plan

Langtail

The useful idea is treating prompts like code that needs a test suite, and then handing the editing surface to people who do not write code. Cross-model replay makes swapping providers a measurable decision rather than a leap, and the firewall covers a risk most prompt tools ignore entirely. The step from free to 99 dollars a month is abrupt for a solo developer, and a Czech company of this size is a smaller bet than the observability platforms it competes with.

Pros

• +Spreadsheet-style prompt editing that non-developers can actually use
• +Test suites and validation runs against saved cases before deployment
• +Replay across models and parameter settings for direct comparison
• +AI Firewall screens for prompt injection and unsafe output
• +Typed TypeScript SDK plus OpenAPI, and a self-hosting option

Cons

• −Only one intermediate tier: free, then 99, then 499 dollars a month plus VAT
• −No pricing anywhere on the marketing pages, only on the plan page
• −Small vendor, and the company gives its details only inside the privacy policy
• −Prices are quoted excluding VAT, so the EU figure is higher than the sticker

Is Langfuse cheaper than Langtail?

On published entry prices, Langfuse starts lower — $29/mo against $99/mo for Langtail. Entry price is the lowest paid plan as we last verified it; what each plan includes differs.

Does Langfuse or Langtail have a free tier?

Both: Langfuse has a free tier, and Langtail has a free tier.

Which has a public API, Langfuse or Langtail?

Both ship a public API, so either can be built on; the fact table above shows the platforms each one runs on.