Comparison
Logfire vs Arize AX
Arize offers two products: Phoenix, an open source tool for LLM tracing and evaluation, and Arize AX, a commercial SaaS platform for ML and AI monitoring. This page compares Logfire against Arize AX.
Feature Comparison
Quick comparison
| Feature | Logfire | Arize AX |
|---|---|---|
| Observability scope | Full-stack (AI + databases, APIs, infra) | AI/LLM tracing + ML model monitoring |
| Strength | Application tracing + AI | drift detection, model performance, agent evaluation |
| Non-AI tracing | Full support | OTel-compatible but no first-class support for web frameworks or databases |
| Language support | Python, JS/TS, Rust + any OTel | Python-focused |
| Pricing | $2/million spans + $25/seat (if more than 5 seats) | $10/million spans + $3/GB payload (AX Pro) |
| Data retention | 30 days default; 90 days (Growth); custom on Enterprise | 15 days on AX Pro; custom on Enterprise |
| Query interface | Standard SQL (PostgreSQL) | Proprietary DSL (Python expression syntax) |
| Language support | Python, JS/TS, Rust + any OTel language | Python-focused |
| Human annotations | Not available | Built in |
| MCP server | Yes | Not available |
Cost Savings
Pricing comparison
| Workload | Arize AX | Logfire | Difference |
|---|---|---|---|
| 1 user, 5M spans/mo | ~$99 | $0 (free tier) | ~$99/mo |
| 5 users, 50M spans/mo | ~$999 | ~$129 | ~8x |
| 20 users, 500M spans/mo | ~$12,249 | ~$1,229 | ~10x |
*Arize Phoenix Cloud (AX) Pro pricing ($10/million spans + $3/GB payload). Logfire Cloud Team or Growth plans ($2/million spans). Arize's dual-axis billing particularly impacts RAG architectures where retrieval context adds significant payload size per trace.
Key Differences
Why teams choose Logfire
One trace, complete context
When something breaks in production, you need to know whether it was the model, the data, or the infrastructure. Arize AX shows you the AI layer. Logfire shows you the whole thing: the user request, the database query, the LLM call, the API response. One trace, complete context. Arize AX can receive OTel spans from non-AI services, but has no first-class support for web frameworks or databases.
Simpler pricing, better retention
Logfire charges $2 per million spans, flat. No payload surcharge. You can afford to ingest everything, which means when something fails in production, the trace is complete and easier to debug and recover.
Standard SQL, no proprietary query language
Logfire uses standard (PostgreSQL) SQL throughout. Your team already knows it. AI coding assistants write excellent SQL, which means you can ask questions about your production traces without leaving your editor. Logfire also ships an MCP server. Point your coding agent at your Logfire data and it can answer arbitrary questions about production production behavior directly, something no proprietary query language makes easy.
Decision Guide
Which should you choose?
Choose Logfire if...
- ✓You need to trace your entire app, not only AI calls
- ✓You have services in multiple languages
- ✓You want the simplest possible setup (3 lines of code)
- ✓You prefer one tool for both AI and application monitoring
- ✓You want to query traces with SQL or via an MCP server
Choose Arize AX if...
- •Your team thinks in ML metrics, not application traces
- •You want human-in-the-loop annotations built-in
- •You're already invested in Arize's broader ML platform
FAQ
Common questions
Ready to switch from Arize AX?
Get started with 10 million free spans per month. No credit card required.