Oren Cohen·Published ·Sources reviewed October 6, 2026·7 min read
The main Langfuse alternatives in 2026: Opik and Arize Phoenix if you want to stay self-hosted, LangSmith for LangChain depth and code-fix proposals, Braintrust for evaluation depth, and W&B Weave or Datadog if you already use them. Converra is different: it adds verified fixes on top of any of them.
Converra is our product, so it is labeled as a complement rather than ranked against the others. Every vendor statement below comes from that vendor's own documentation or pricing page, checked on October 6, 2026.
The short version
If you chose Langfuse for open source and self-hosting, Opik and Phoenix are the closest swaps. If you want fixes proposed for you, look at Opik, LangSmith, Braintrust, or Datadog. None of them returns a per-deploy verdict on whether a fix worked; that is the gap Converra fills alongside any of them.
Why teams look for a Langfuse alternative
Langfuse covers tracing, LLM-as-a-judge evaluation, experiments with CI checks, and prompt management, and it is free to self-host. Teams usually look elsewhere when they want the tool itself to analyze failures and propose fixes, built-in multi-turn simulation, or a managed platform they already pay for.
Langfuse says it stays open source and self-hostable with no planned licensing changes. See the Langfuse vs Converra comparison for how Converra works alongside it.
How we compared
We read each vendor's current documentation, pricing, and license on October 6, 2026, and compared the same things: how tracing works, evaluation and simulation, whether the tool proposes fixes, how prompts reach production, whether anything measures a change after release, hosting, and starting price.
We did not run hands-on benchmarks, and the order below groups tools by the need they serve rather than by a quality score. Prices change often; check each vendor's pricing page before deciding.
Best all-in-one open source
Opik by Comet
Apache-2.0 platform for tracing, evaluation, prompt management, and production monitoring, with built-in user simulation and an agent optimizer.
Best for: teams that want the widest open-source feature set, including simulation and fix suggestions, at a low entry price.
Apache 2.0 license; self-host free with the full feature set
Built-in multi-turn evaluation with a simulated user
Diagnostics groups matching failures into issues with a likely root cause and suggested fix
Pro Cloud from $19 per month
Diagnostics requires the Ollie assistant and consumes its tokens
No documented promotion of prompts to production or post-release verdict
Best for OpenTelemetry-native tracing
Arize Phoenix
Arize's source-available tracing and evaluation tool built on OpenTelemetry and OpenInference, with Arize AX as the managed product.
Best for: teams that want free self-hosted tracing on open standards, with an upgrade path to a managed platform.
Built on OpenTelemetry with OpenInference instrumentation for many agent frameworks
LLM, code-based, and human evaluations, with datasets and experiments
Prompt versions with production, staging, and development tags
Arize AX adds the Alyx agent and prompt optimization
Elastic License 2.0, which is source-available rather than OSI open source
Fix proposals live mainly in the managed Arize AX product
Not a tracing tool. Converra reads your traces, diagnoses recurring failures, tests prompt or configuration fixes head-to-head against the current agent, ships what you approve, and returns a production verdict.
Best for: teams that keep their tracing tool and want fixes tested before release and judged on live traffic as verified, not fixed, or confounded.
Connectors for LangSmith and Langfuse; other data through its SDK or traces API
Head-to-head multi-turn simulation against the current agent, with regression scenarios
A production verdict on every fix it ships
Does not replace tracing, datasets, or prompt management
Built for conversational agents; LangSmith single-turn traces are skipped
One row per tool, on the dimensions that usually decide the choice. A dash means the vendor documentation we reviewed did not describe the capability.
Langfuse alternatives compared, as of October 6, 2026
Tool
License and hosting
Proposes fixes
Starting paid price
Opik
Apache 2.0; free self-hosting
Yes, Diagnostics with Ollie
$19 per month (Pro Cloud)
Arize Phoenix
Elastic License 2.0; free self-hosting
In Arize AX (Alyx)
AX Pro $50 per month
LangSmith
Proprietary; self-hosting as Enterprise add-on
Yes, Engine pull requests
$39 per seat per month (Plus)
Braintrust
SaaS; Enterprise self-hosted data plane
Yes, Loop and Patterns
$249 per month (Pro)
W&B Weave
SaaS, dedicated, or self-managed
—
$60 per month (Pro)
Datadog
SaaS only
Yes, Insights recommend fixes
Check with Datadog
Converra
Managed; Enterprise on-prem or VPC option
Yes, tested head-to-head before release
See pricing page
Tool
Opik
License and hosting
Apache 2.0; free self-hosting
Proposes fixes
Yes, Diagnostics with Ollie
Starting paid price
$19 per month (Pro Cloud)
Tool
Arize Phoenix
License and hosting
Elastic License 2.0; free self-hosting
Proposes fixes
In Arize AX (Alyx)
Starting paid price
AX Pro $50 per month
Tool
LangSmith
License and hosting
Proprietary; self-hosting as Enterprise add-on
Proposes fixes
Yes, Engine pull requests
Starting paid price
$39 per seat per month (Plus)
Tool
Braintrust
License and hosting
SaaS; Enterprise self-hosted data plane
Proposes fixes
Yes, Loop and Patterns
Starting paid price
$249 per month (Pro)
Tool
W&B Weave
License and hosting
SaaS, dedicated, or self-managed
Proposes fixes
—
Starting paid price
$60 per month (Pro)
Tool
Datadog
License and hosting
SaaS only
Proposes fixes
Yes, Insights recommend fixes
Starting paid price
Check with Datadog
Tool
Converra
License and hosting
Managed; Enterprise on-prem or VPC option
Proposes fixes
Yes, tested head-to-head before release
Starting paid price
See pricing page
What none of these do: say whether the fix worked
Several tools now find recurring failures and propose fixes. After a change ships, LangSmith Engine reopens an issue if it recurs, Datadog Insights resolve when a problem stops appearing, Braintrust lets you track whether a problem declined, and Langfuse shows metrics per prompt version. None of the documentation we reviewed describes a verdict tied to a specific deployment that also accounts for other changes in the same window.
That is the job Converra does next to whichever tool you pick: it measures the targeted failure on live traffic after a fix ships and marks it verified, not fixed, or confounded. The guide to verifying a fix after deployment explains why per-version metrics are correlational.
Why Helicone is not on this list
Helicone was acquired by Mintlify in March 2026 and says its services will remain live in maintenance mode, with security patches and bug fixes. It still works as a self-hosted gateway, but it is a poor choice for a new long-term commitment.
What is the best open-source alternative to Langfuse?
Opik is the closest open-source alternative: it is Apache 2.0, self-hosts for free with the full feature set, and adds built-in user simulation and fix suggestions. Arize Phoenix is also free to self-host but uses the Elastic License 2.0.
Is Langfuse still open source after the ClickHouse acquisition?
Langfuse announced in January 2026 that it joined ClickHouse, stays open source and self-hostable, and has no planned licensing changes.
Which Langfuse alternative can propose fixes?
Opik's Diagnostics, LangSmith Engine, Braintrust's Loop and Patterns, Datadog's Insights, and Arize AX's Alyx all propose fixes in some form. Converra generates prompt or configuration fixes and tests them head-to-head against the current agent before release.
Is Converra a Langfuse alternative?
Not for tracing. Converra imports Langfuse traces, including from self-hosted instances, and adds fix generation, head-to-head simulation, and a production verdict. You keep Langfuse for tracing and evaluation.
How current is this comparison?
Vendor documentation and prices were checked on October 6, 2026. These products change monthly, so confirm anything decisive on the vendor's own site.
Founder of Converra. Previously founded Buildup (acquired by Stanley Black & Decker) and, as VP Product Growth at Totango, owned AI end-to-end from design through production.
Converra connects to Langfuse Cloud, self-hosted Langfuse, or LangSmith, diagnoses recurring failures, tests fixes against your current agent, ships what you approve, and returns a production verdict: verified, not fixed, or confounded.
