Query Traces

Langfuse is open-source and data tracked with Langfuse is open. You can query/export data via: SDKs, API, and Langfuse UI.

Common use cases:

• Train or fine-tune models on the production traces in Langfuse. E.g. to create a small model after having used a large model in production for a specific use case.
• Collect few-shot examples to improve quality of output.
• Programmatically create datasets.

Want to learn more about the Langfuse data model? Check out our introduction to tracing in Langfuse.

SDKs

Via the SDKs for Python and JS/TS you can easily query the API without having to write the HTTP requests yourself.

pip install langfuse

from langfuse import Langfuse
langfuse = Langfuse(
  secret_key="sk-lf-...",
  public_key="pk-lf-...",
  host="https://cloud.langfuse.com"  # 🇪🇺 EU region
  # host="https://us.cloud.langfuse.com" # 🇺🇸 US region
)
 
# Fetch list of traces, supports filters and pagination
traces = langfuse.fetch_traces()
 
# Fetch a single trace by ID
trace = langfuse.fetch_trace("traceId")
 
# Fetch list of observations, supports filters and pagination
observations = langfuse.fetch_observations()
 
# Fetch a single observation by ID
observation = langfuse.fetch_observation("observationId")
 
# Fetch list of sessions
sessions = langfuse.fetch_sessions()

API

All data in Langfuse is available via the API. Refer to the API reference (opens in a new tab) for more information.

Example routes:

GET /api/public/traces
GET /api/public/traces/:traceId
 
GET /api/public/observations
GET /api/public/observations/:observationId
 
GET /api/public/sessions
 
GET /api/public/scores
GET /api/public/scores/:scoreId

Export via UI

All filters applied to the table will be applied to the export.

Available export formats:

• CSV
• JSON

Trouble exporting?

If you're having trouble exporting data, please let us know and we'll help you out.