o4 Mini Deep Research Playground for Deep Research Evals

A o4 Mini Deep Research Playground for Deep Research Evals deep research playground is a UI for prompt testing and evals on research-style tasks—structured prompts, repeatable runs, and comparisons against other models.

Evaluating research behavior: coverage, structure, reasoning quality, and consistency across repeated runs—without building a research pipeline first.

Yes. Bring your API keys. LangFast routes requests through our proxy.

To prevent abuse, keep free limits fair, and let you save research runs, reuse prompt sets, and share results with collaborators.

Coverage (did it miss key angles?), structure (outline quality), faithfulness to constraints, and how reliably it follows your requested format.

Rerun the same research brief multiple times and compare: do the main claims drift, does structure collapse, do key sections disappear?

Yes. Define criteria like “coverage, specificity, actionability, clarity” and score outputs consistently across runs and models.

Yes. Run the same brief side-by-side to decide if deeper output quality is worth the extra cost/latency.

Yes. Evaluate outputs as memos, PRDs, competitive analyses, briefs, checklists, or structured tables—whatever you need to ship.

If your workflow requires citations, add explicit constraints and test whether the model follows them consistently (and how it behaves when uncertain).

Yes. Save a research prompt set and rerun it after model changes or prompt edits to detect regressions in coverage and structure.

Yes. Inject product context, customer segments, constraints, and real inputs to make research prompts production-like.

Yes—export to cURL/JS/JSON so the exact call can be reproduced programmatically.

Yes. Share links for review, edits, or stakeholder alignment.

LangFast is free to use with some basic features. You need to provide your own API keys to run models and use the app. When you add your API keys, you pay the model provider (e.g., OpenAI) for the credits/tokens you use. LangFast premium features can be unlocked with a one-time purchase.

Wait for the reset or add paid usage to keep running research evaluations.

We stream responses through a lightweight proxy. Research tasks vary by model and load; compare latency across models directly.

No. We don’t train on your prompts or data. Sharing is opt-in and retention is configurable.

Requests route to model providers. See the Data & Privacy page for processing regions and details.

LangChain is for building research agents and pipelines. LangFast is for testing research prompts and evaluating outputs before you build automation.

Those tools help manage datasets, tracing, and evals in workflows. LangFast is a fast interactive bench to compare research outputs and pick prompts/models first.