Best LLM & Agent Infrastructure for startups
Last verified:
Crail tracks 10 LLM & Agent Infrastructure vendors that list startups as a fit. These are the 5 that rank highest once the list is weighted for startups, and each one is shown with what it costs to start and whether you can start today without a contract — the facts that decide the shortlist at this size, rather than the same summary on every page.
How this list is weighted for startups
- 60% of the vendor's Crail agent-readiness score
- 15 points for a published free tier
- 15 points for being buyable self-serve, without a sales call
- up to 10 points for a low entry price (free tier, then a cheapest paid tier under $30, then under $75)
Startups and small businesses share the price-and-self-serve weighting; midmarket and enterprise share the compliance weighting. The full rules are on the methodology page.
Best overall: Braintrust
Open-source option: Langfuse
1. Braintrust88/100 agent-readiness
Eval-first observability and experimentation platform for building and monitoring high-quality LLM/agent apps.
- Free tier: yes
- Open source: no
- Buy self-serve: yes
- Cheapest paid tier: Pro at $249/month
2. Arize Phoenix86/100 agent-readiness
Open-source LLM tracing, evaluation, and experimentation platform built on OpenTelemetry, by Arize AI.
- Free tier: yes
- Open source: yes (10,700 GitHub stars)
- Buy self-serve: yes
- Cheapest paid tier: Arize AX Pro at $50/month
3. Helicone85/100 agent-readiness
Open-source LLM observability platform and AI gateway for monitoring, evaluating, and optimizing LLM apps.
- Free tier: yes
- Open source: yes (5,998 GitHub stars)
- Buy self-serve: yes
- Cheapest paid tier: Pro at $79/month
4. Langfuse85/100 agent-readiness
Open-source LLM engineering platform for tracing, evals, prompt management, and observability of LLM apps and agents.
- Free tier: yes
- Open source: yes (31,895 GitHub stars)
- Buy self-serve: yes
- Cheapest paid tier: Core at $29/month
5. Weights & Biases Weave84/100 agent-readiness
W&B Weave is Weights & Biases' toolkit for tracing, evaluating, and monitoring LLM apps and agents in production.
- Free tier: yes
- Open source: no
- Buy self-serve: yes
- Cheapest paid tier: Pro at $60/month
FAQ
How is this LLM & Agent Infrastructure ranking calculated for startups?
This is not the raw agent-readiness leaderboard. Crail scores the 10 LLM & Agent Infrastructure vendors it tracks that fit startups, using 60% of the vendor's Crail agent-readiness score; 15 points for a published free tier; 15 points for being buyable self-serve, without a sales call; up to 10 points for a low entry price (free tier, then a cheapest paid tier under $30, then under $75). Braintrust ranks first on both measures: it holds the highest raw agent-readiness score on this list (88/100) and the top score once the startups weighting is applied.
Which of these can a startup use without paying?
All 5 publish a free tier: Braintrust, Arize Phoenix, Helicone, Langfuse and Weights & Biases Weave. Arize Phoenix, Helicone and Langfuse are open source, so they can also be self-hosted without a license fee.
Do any of them require a sales call before you can buy?
No. All 5 can be bought self-serve, without talking to sales.