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Side-by-side features, use cases and pricing — because the right pick depends on your job and budget, not just the ranking.

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Openlit logo
Openlit
✓ verifiedFreemium

Open-source, OpenTelemetry-native platform for LLM observability, tracing, evaluation and prompt management.

9.1K visits/mo
Latitude logo
Latitude
✓ verifiedFreemium

Open-source AI-agent observability platform for tracing sessions, clustering failures and running evals on live traffic.

57K visits/mo
liteLLM logo
liteLLM
✓ verifiedFreemium

Open-source AI gateway giving dev teams unified access, fallbacks and spend tracking across 100+ LLMs.

703K visits/mo
Arize AI logo
Arize AI
✓ verifiedFreemium

AI observability and evaluation platform to trace, evaluate and improve LLM agents in production, with an open-source Phoenix core.

248K visits/mo
ApX Machine Learning logo
ApX Machine Learning
✓ verifiedFreemium

Tools, model specs and courses for LLM engineers-VRAM calculator, benchmarks and model directory-with free and paid tiers.

355K visits/mo
Pricing
Self-Hosted: $0 (Apache 2.0, no usage limits)

No public pricing

Open Source: $0 (self-hosted, 100+ providers)

Free trial available

AX Free: $0/mo (25k spans/mo)
AX Pro: $50/mo (50k spans/mo)
Basic: $0/mo (free forever)
Pro: $19/mo
Pro+: $59/mo
Core features
  • OpenTelemetry-native distributed tracing
  • Token usage and cost tracking
  • LLM evaluations (online/offline)
  • Prompt management and versioning
  • GPU and vector-DB monitoring
  • 60+ LLM/framework integrations
  • Self-hostable via Docker; export to Grafana/Datadog
  • Agent trace capture and conversation intelligence
  • Semantic and exact-text search across all traces
  • Automatic issue discovery with Slack/email/webhook alerts
  • OpenTelemetry-compatible SDK with no lock-in
  • Automated evals and golden dataset generation
  • Failure-mode clustering and MCP server integration
  • Unified access to 100+ LLMs in OpenAI format
  • Cost/spend tracking per key, user and team
  • Budgets and rate limiting
  • Automatic provider fallbacks and retries
  • Virtual keys and team management
  • Logging and observability integrations
  • Agent and LLM tracing
  • Large-scale evaluations
  • Open-source Phoenix observability
  • Alyx AI engineering agent
  • OpenTelemetry-based instrumentation
  • Experiments and prompt playgrounds
  • VRAM/GPU-memory calculator for LLMs
  • LLM performance rankings and benchmarks
  • Model directory and comparison
  • AI/ML courses and learning roadmap
  • Calculator API and exportable cost reports
  • Engineering blog and guides
Use cases
  • Trace and debug LLM applications
  • Monitor AI cost and performance
  • Evaluate prompts and models
  • Add observability without code changes
  • Monitoring AI agents in production
  • Debugging and triaging agent failures
  • Building regression evals from real traffic
  • Getting alerted on new or escalating issues
  • Giving developers governed access to many LLMs
  • Attributing and controlling LLM spend
  • Keeping apps running during provider outages
  • Debugging AI agents in production
  • Measuring LLM output quality
  • Catching regressions before deploy
  • Estimating GPU memory before training or inference
  • Comparing and selecting LLMs
  • Learning ML and LLM engineering
  • Modeling production deployment costs
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