PromptLayer

PromptLayer is a prompt management and LLM observability platform whose original differentiator was treating prompts as first-class assets, versioned and edited outside of code. Engineers add a small SDK to their app; PromptLayer then logs every LLM call with the model, parameters, prompt template, latency, and cost. Product managers, prompt engineers, and subject matter experts can edit prompts in the PromptLayer web UI without shipping code — the SDK fetches the latest published version (or a pinned tag) at runtime. The platform also offers backtests against historical traffic, evaluation pipelines with custom and LLM-as-judge scorers, A/B testing for prompt variants, and analytics on which prompts are improving real-world outcomes. PromptLayer integrates with OpenAI, Anthropic, Google, Mistral, and most major providers. The product is widely used at companies where prompt iteration is owned partly by non-engineers — content teams, ML PMs, legal/policy reviewers — because it gives them a sandbox without giving them production code access. Pricing pages exist (the marketing site was extracted as styled-components CSS during automated fetch), and tiers traditionally include a free hobby plan, a per-seat team plan, and an enterprise tier — but exact 2026 numbers need manual verification.