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Langfuse

Langfuse UnstableEvaluators API

The UnstableEvaluators API from Langfuse — 2 operation(s) for unstableevaluators.

Documentation Provider Profile APIs.io OpenAPI GitHub

Langfuse UnstableEvaluators API is one of 28 APIs that Langfuse publishes on the APIs.io network, described by a machine-readable OpenAPI specification.

Tagged areas include UnstableEvaluators. The published artifact set on APIs.io includes an OpenAPI specification, API documentation, and an API reference.

This API exposes 3 operations across 2 paths, and defines 19 schemas. It is described by OpenAPI 3.0.1, at version 1.0.

Requests are made against the base URL https://cloud.langfuse.com/api/public.

3 operations 2 paths 19 schemas 2 GET1 POST

Metadata

The identity and technical contract details declared by the specification.

Specification
OpenAPI 3.0.1
API Version
1.0
Base URL
https://cloud.langfuse.com/api/public
Authentication
HTTP Basic
Resource Areas
1

Authentication & Security 1

Langfuse UnstableEvaluators API declares 1 security scheme for authenticating requests. It accepts HTTP basic authentication (BasicAuth).

Paths & Operations 3

Across 2 paths, the API surfaces 3 operations — 2 GET, 1 POST. Each is listed below with its method, path, parameters, and response codes.

UnstableEvaluators 3
POST
/api/public/unstable/evaluators
Create an evaluator in the authenticated project. Use evaluators to define how Langfuse should score data: the prompt, the expected structured output, and the optional model configuration. Naming beh…
unstable_evaluators_create body → 200400401403404405409422
GET
/api/public/unstable/evaluators
List the evaluators available to the authenticated project. Important behavior: - This endpoint returns the latest version of each available evaluator. - Results can include evaluators from your proj…
unstable_evaluators_list 2 params → 200400401403404405429500
GET
/api/public/unstable/evaluators/{evaluatorId}
Get one evaluator by id. Use this endpoint when you want the prompt, output definition, model configuration, and derived variables for the evaluator you plan to use in an evaluation rule.
unstable_evaluators_get 1 param → 200400401403404405429500

Schemas 19

The contract defines 19 schemas that model the data the API accepts and returns. The most detailed are unstablePublicApiErrorDetails (15 properties), unstableEvaluator (12 properties), unstableCreateEvaluatorRequest (4 properties), utilsMetaResponse (4 properties). Each schema is shown below with its type and property counts.

utilsMetaResponse
object
4 properties 4 required
unstableEvaluatorModelConfig
object
Optional explicit model configuration for an evaluator. If omitted, Langfuse uses the project's default evaluation model. If provided, the model must be availa…
2 properties 2 required
unstablePublicCategoricalEvaluatorOutputDefinition
object
3 properties 3 required
unstablePublicCategoricalEvaluatorOutputScoreDefinition
object
3 properties 3 required
unstablePublicBooleanEvaluatorOutputDefinition
object
3 properties 3 required
unstableEvaluatorOutputDataType
string
Structured score type returned by an evaluator. This controls the type of score value Langfuse stores for evaluation results: - NUMERIC: a numeric score such a…
unstableCreateEvaluatorRequest
object
Request body for creating an evaluator. If the same name already exists in your project, Langfuse creates the next version and returns it. Existing evaluation…
4 properties 3 required
unstableEvaluator
object
One evaluator that can be used for scoring. An evaluator describes how to score data: - prompt - extracted prompt variables - output schema - optional explicit…
12 properties 11 required
unstablePublicApiErrorCode
string
Machine-readable error code returned by the unstable evaluators API. SDKs, CLIs, and agents should branch on code rather than parsing the human-readable messag…
unstablePublicApiError
object
Standard error envelope for the unstable evaluators API. Response handling guidance: - Use the HTTP status code for the broad class of failure. - Use code for…
3 properties 2 required
unstablePublicApiErrorDetails
object
Optional structured context attached to an unstable-evals error. The populated fields depend on the error code: - request parsing failures populate issues - fi…
15 properties
unstablePublicNumericEvaluatorOutputDefinition
object
3 properties 3 required
unstablePublicApiValidationIssue
object
One validation issue returned for malformed request bodies or query parameters. This mirrors the most important parts of a Zod issue: a machine-readable code,…
3 properties 3 required
unstableEvaluators
object
2 properties 2 required
unstableEvaluatorScope
string
Where an evaluator comes from. - project: created in your project - managed: provided by Langfuse
unstableEvaluatorType
string
The evaluator engine type. The unstable public API currently supports only LLM-as-a-judge evaluators.
unstableEvaluatorOutputDefinition
Structured output definition to send when creating an evaluator. Agent guidance: - dataType is required. - Do not send version; that is an internal storage det…
unstableEvaluatorOutputFieldDefinition
object
1 property 1 required
unstablePublicEvaluatorOutputDefinition
Evaluator output definition returned by the public API. This response always includes dataType and never includes an internal output-definition version. Legacy…

Specification

The full machine-readable OpenAPI contract behind this narrative.

Source

langfuse-unstableevaluators-api-openapi.yml Raw ↑

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#UnstableEvaluators
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API Details
ID
langfuse:langfuse-unstableevaluators-api
Base URL
https://cloud.langfuse.com/api/public
Docs
https://langfuse.com/docs/tracing
Provider
Langfuse
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