tensorzero

library2026.5.0pypypi✓ verified 85d ago

The Python client for TensorZero, an open-source platform for optimizing and evaluating LLM applications. Current version 2026.5.0, requires Python >=3.10. Released approximately monthly.

llm-agents ai-ml observability

pip install tensorzero

github ↗package ↗homepage ↗docs ↗

INSTALL

IMPORT

SIG · TENSORZERO

tensorzero

llm-agentspythonv2026.5.0

harness data pending

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.

TensorZeroGateway

✓ from tensorzero import TensorZeroGateway

✗ from tensorzero import Client

The main client class was historically named 'Client' but is now 'TensorZeroGateway' in modern versions.

inference

✓ from tensorzero import inference

Direct import of inference function

Initialize TensorZero client and make a simple inference.

from tensorzero import TensorZeroGateway # Initialize client pointing to your TensorZero gateway client = TensorZeroGateway(base_url='http://localhost:3000') # Make an inference response = client.inference( function_name='chatbot', input={ 'messages': [ {'role': 'user', 'content': 'Hello!'} ] } ) print(response['output']['content'])

Debug

Known issues

breakingVersion 2026.5.0 changes UI authentication: when gateway requires auth, UI now also requires auth.

fix

Ensure your gateway and UI authentication settings are consistent.

affects: >=2026.5.0

breakingVersion 2026.4.1 defaults to async observability writes, reducing tail latency.

fix

To restore synchronous writes, set `observability.async_writes = false` in gateway config.

affects: >=2026.4.1

breakingVersion 2026.2.2 changes config-file globbing: single-level wildcards no longer match across directories.

fix

Use `**` for recursive globbing, e.g., `--config-file **/*.toml`.

affects: >=2026.2.2

breakingVersion 2026.2.1 changes default `cache_options.enabled` from `write_only` to `off`.

fix

If you rely on caching, set `cache_options.enabled = 'write_only'` explicitly.

affects: >=2026.2.1

deprecatedLegacy inference evaluations format (flat under `[evaluators]`) is deprecated since 2026.3.4.

fix

Nest evaluators under functions: `[functions.my_func.evaluators.exact_match]`.

affects: >=2026.3.4

deprecatedThe `model_provider_name` filter for `extra_body` and `extra_headers` was removed in 2026.3.1.

fix

Use `model_name` and `provider_name` instead.

affects: >=2026.3.1

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'tensorzero'

Package not installed or installed in wrong environment.

fix

Run `pip install tensorzero` in the correct Python environment (Python >=3.10).

ImportError: cannot import name 'Client' from 'tensorzero'

The client class was renamed from `Client` to `TensorZeroGateway` in a past breaking change.

fix

Use `from tensorzero import TensorZeroGateway` instead.

tensorzero.config.ConfigError: config file not found

The gateway requires a configuration file (e.g., `tensorzero.toml`) in the specified path.

fix

Ensure the config file exists and use `--config-file` with correct path (use `**/*.toml` for recursive search).

tensorzero.gateway.GatewayError: inference failed: ...

Inference request failed due to invalid input, missing API keys, or provider errors.

fix

Check the response status code and error message. Verify your input schema and ensure provider API keys are set.

Upgrade

Version history

2026.5.0latest on PyPI · released May 8, 2026

Audit

Dependencies

openaioptionalTensorZero wraps OpenAI-compatible APIs and may use client internally

httpxrequiredUsed for HTTP requests to the TensorZero gateway

Agent activity

40 hits · last 30 days

node

Bingbot

OpenAI (training)

Resources

githubhttps://github.com/tensorzero/tensorzero ↗

packagehttps://pypi.org/project/tensorzero/ ↗

homepagehttps://tensorzero.com/ ↗

docshttps://tensorzero.com/docs/ ↗