— Infrastructure Tool

PromptLayer

Last updated 2026-07-11 · Reviewed by ToolForge Editorial

The first platform built for prompt engineering — versioning, logging, and A/B testing for LLM calls.

★ 4.2/5 · 12K+ devs · Since 2023 · Free (limited logs)

Git for your prompts

PromptLayer records every LLM call your app makes, lets you version prompts, and test variants side by side — the fastest way to stop guessing about what works.

Who it's for: Indie hackers and engineering teams who ship LLM features and need to see what's actually happening in production.

Key features

Request logging

Every prompt and completion, searchable and replayable.

Prompt versioning

Tag and compare prompt versions over time.

A/B testing

Split traffic between prompt variants and measure quality.

Collaboration

Share logs and prompts with your whole team.

The honest take

✓ What works

  • Dead-simple drop-in logging
  • Great for debugging prod LLM issues
  • Free tier is useful
  • Lightweight compared to full platforms

✗ What doesn't

  • Less depth than full MLOps suites
  • UI can feel busy
  • Alerting is basic on free
  • Best for OpenAI-style APIs

Verdict

PromptLayer is the lowest-friction way to get visibility into your LLM app. If you're flying blind on what your prompts actually return, install it today — the free tier is plenty to start.

💡 Transparency: This review contains affiliate links. If you sign up through our link, we may earn a commission at no cost to you. We only recommend tools we use ourselves. Full disclosure.

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