Install & Compatibility
Where this runs
No compatibility data collected yet for this library.
Code
Verified usage
Verified import paths — ran on the pinned version, not inferred.
Tru
✓ from trulens.core import Tru
✗ from trulens import Tru
In v2.x, Tru moved to trulens.core
Feedback
✓ from trulens.core import Feedback
✗ from trulens import Feedback
Feedback also moved to trulens.core
Select
✓ from trulens.core import Select
✗ from trulens import Select
Select moved to trulens.core
Initialize TruLens, create a feedback function with OpenAI, wrap a custom app, run it, and view leaderboard.
import os
from trulens.core import Tru, Feedback
from trulens.providers.openai import OpenAI
tru = Tru()
provider = OpenAI(api_key=os.environ.get('OPENAI_API_KEY', ''))
# Define a feedback function
feedback = Feedback(provider.relevance).on_input_output()
# Wrap an app (example using a dummy function)
from trulens.apps.custom import TruCustom
def my_app(input: str) -> str:
return f"Response to: {input}"
tru_app = TruCustom(my_app, app_name='MyApp', feedbacks=[feedback])
# Run the app
with tru_app as recording:
recording.record(my_app, "Hello, world!")
# Check results
tru.get_leaderboard()
Errors
Common errors & fixes
ModuleNotFoundError: No module named 'trulens'
TruLens not installed or installed in wrong environment.
fixRun 'pip install trulens' and ensure you are using Python >=3.10.
AttributeError: module 'trulens' has no attribute 'Tru'
Using old import path; in v2.x, Tru is in trulens.core.
fixChange import to 'from trulens.core import Tru'.
ValueError: Feedback function 'relevance' has no provider
Feedback function requires a provider (e.g., OpenAI) to be instantiated.
fixInstantiate a provider: 'provider = OpenAI(api_key=...)' and pass it to Feedback constructor.
Upgrade
Version history
2.8.1latest on PyPI · released May 14, 2026
Audit
Dependencies
openaioptionalOptional provider for LLM feedback functions
langchainoptionalOptional integration with LangChain
llama-indexoptionalOptional integration with LlamaIndex