What is Braintrust?

Braintrust is an evaluation and observability platform for teams building LLM apps. Its core workflow turns production traces into datasets, runs experiments that compare prompts and models against them, and scores output with code-based or LLM-as-judge scorers. Playgrounds, human review, and an AI agent called Loop that builds scorers and datasets from your data sit in the same workspace.

Pricing combines a flat platform fee with two usage meters, processed data and scores, and every plan includes unlimited users. The free Starter plan keeps data for 14 days, Pro keeps it for 30 days at $249 a month, and longer retention costs $0.50 per GB per month. Because both meters grow with eval volume, a larger test suite can move the bill as much as production traffic does. Self-hosting is only available on Enterprise.

Braintrust also runs a hosted gateway with caching and provider failover, which replaced its deprecated AI proxy and is currently in public preview with no SLA. If you need routing backed by an uptime commitment, the Braintrust alternatives worth comparing include platforms that combine a production gateway with tracing and evals.

Key features

Core capabilities this platform advertises.

Experiments comparing prompts and models
Code-based and LLM-as-judge scorers
Datasets built from production traces
Production logging and tracing

Strengths and tradeoffs

What this tool does well, and the limitations to keep in mind.

Pros

Unlimited users on every plan, including free
Production traces, datasets, and experiments connect in one eval workflow
Framework-agnostic SDKs across multiple languages
Loop agent drafts scorers and datasets from your own data

Cons

Processed data and scores bill separately, and both grow with eval volume
14-day retention on Starter and 30 days on Pro
Gateway is in public preview with no SLA
Self-hosting and custom data export are Enterprise only

Plans & pricing

What's included in each plan, and how the tiers compare.

Starter

Free

1 GB processed data, then $4/GB
10K scores, then $2.50 per 1K
$10 in model credits
14-day retention
Unlimited users

Pro

$249

Per month

5 GB processed data, then $3/GB
50K scores, then $1.50 per 1K
$100 in model credits
30-day retention, then $0.50/GB/month

Enterprise

Custom

Contact sales for a quote

Custom data retention and export
On-prem or hosted deployment
Premium support

View official pricing page

Common use cases

Teams that want structured evals, experiments, and datasets tied to production traces

Iterating on prompts with production data
Running evaluations across model versions
Building golden datasets from production traffic
Human review of LLM outputs

Using Braintrust with Respan

Respan's Braintrust instrumentation registers as Braintrust's background logger, so the spans your Braintrust code already produces flow into Respan, with prompts, completions, model, and token usage on LLM spans. Add Respan's gateway, and each request is routed across 1,000+ models, traced, and scored on the same record.

Send existing Braintrust spans to Respan with one instrumentor
Route across 1,000+ models with a 99.9% uptime SLA on Team
Score output on live production traffic with automated evals
Trace, cost, and eval score for each request on one record

Score live production traffic with Respan

10KFree traces/mo

1,000+Models

5 minSetup

Respan routes every call across 1,000+ models, traces it, and scores output on live traffic, so the trace, cost, and eval score sit on one record. Start free.

Try Respan free

Best Braintrust alternatives & competitors

Top companies in Observability, Prompts & Evals you can use instead of Braintrust.

Respan

Nested traces for every LLM call, tool run, and agent turn

Braintrust AI: Evals, Pricing, Pros & Cons