Browser Based Prompt Testing And Iteration

via “interactive playground for prompt testing and iteration”

Open-source LLM observability — tracing, evaluation, OpenTelemetry, span analysis.

Unique: Playground is integrated with Phoenix traces, allowing users to select real historical queries as test inputs without manual copy-paste; supports variable substitution and model comparison in a single interface

vs others: More integrated than standalone prompt testing tools (PromptFoo, LangSmith) because it uses real production data from traces; simpler than code-based prompt testing because no Python/JavaScript required