Opik suits teams developing applications or agents that call an LLM and need to inspect, evaluate, and monitor their behavior.
Free plan Free trial Open source From $19 a month WebWindowsMacLinuxAPISelf-hosted
Best Llm Developer Tools 2026
Facts read 24 Sep 2026 – 21 Oct 2026
LLM developer tools help teams create, connect, assess and observe applications built with language models. This list helps buyers compare options for model access, testing, observability and deployment.
The standings: top 10
| Name | In a line | Record score | Price from | Try it free | Runs on | Facts read |
|---|---|---|---|---|---|---|
| 01 Opik | Opik suits teams developing applications or agents that call an LLM and need to inspect, evaluate, and monitor their behavior. | 6.1 | $19 a month | Free plan | Web, Windows, Mac, Linux | 21 Oct 2026 |
| 02 DeepEval | DeepEval suits developers building repeatable evaluations for AI systems, especially those running tests in Python or CI/CD. | 6.0 | $200 a month | Free plan | Web, Windows, Mac, Linux | 15 Oct 2026 |
| 03 Langfuse | Langfuse suits teams building AI agent applications that need tracing, prompt management, and evaluation tools. | 5.7 | $29 a month | Free plan | Web, Linux, API, Self-hosted | 15 Oct 2026 |
| 04 LangSmith | LangSmith suits teams developing AI agents that need evaluation, prompt tools, tracing, and production monitoring. | 5.3 | $39 usage-based | Free plan | Web, Windows, Mac, Linux | 15 Oct 2026 |
| 05 Promptfoo | Promptfoo is for developers and enterprises building AI applications who need prompt evaluation or red-team testing. | 5.3 | Free plan | Free plan | Web, Windows, Mac, Linux | 15 Oct 2026 |
| 06 Braintrust | Braintrust is intended for teams running AI agents in production, from early-stage projects to enterprise deployments. | 5.0 | $249 a month | Free plan | Web, API, Self-hosted | 15 Oct 2026 |
| 07 Helicone | It suits teams building or operating AI applications that need provider routing, request tracing, or cost visibility. | 5.0 | $79 usage-based | Free plan | Web, API, Self-hosted | 1 Oct 2026 |
| 08 OpenRouter | OpenRouter suits developers and teams that want one API endpoint for access to multiple AI models and providers. | 4.9 | Free plan | Free plan | Web, API | 29 Sep 2026 |
| 09 LangChain | LangChain suits developers building model-and-tool agents in Python or JavaScript/TypeScript. | 4.8 | $39 usage-based | Free plan | API, Self-hosted | 4 Oct 2026 |
| 10 LlamaIndex | LlamaIndex is aimed at developers and enterprises automating document processing and knowledge work. | 4.8 | $50 usage-based | Free plan | Web, Linux, API, Self-hosted | 7 Oct 2026 |
The page orders tools by newest releases first. It uses figures the makers publish and does not score the tools.
02
DeepEval
DeepEval suits developers building repeatable evaluations for AI systems, especially those running tests in Python or CI/CD.
WebWindowsMac+3 Record6.0 Visit
03
Langfuse
Langfuse suits teams building AI agent applications that need tracing, prompt management, and evaluation tools.
WebLinuxAPI+1 Record5.7 Visit
04
LangSmith
LangSmith suits teams developing AI agents that need evaluation, prompt tools, tracing, and production monitoring.
WebWindowsMac+3 Record5.3 Visit
05
Promptfoo
Promptfoo is for developers and enterprises building AI applications who need prompt evaluation or red-team testing.
WebWindowsMac+3 Record5.3 Visit
6
Braintrust
WebAPISelf-hosted $249 a month Record5.0 Visit Braintrust is intended for teams running AI agents in production, from early-stage projects to enterprise deployments.
7
Helicone
WebAPISelf-hosted $79 usage-based Record5.0 Visit It suits teams building or operating AI applications that need provider routing, request tracing, or cost visibility.
8
OpenRouter
WebAPI Free plan Record4.9 Visit OpenRouter suits developers and teams that want one API endpoint for access to multiple AI models and providers.
9
LangChain
APISelf-hosted $39 usage-based Record4.8 Visit LangChain suits developers building model-and-tool agents in Python or JavaScript/TypeScript.
10
LlamaIndex
WebLinuxAPI+1 $50 usage-based Record4.8 Visit LlamaIndex is aimed at developers and enterprises automating document processing and knowledge work.
11
Portkey
WebAPISelf-hosted $49 a month Record4.7 Visit Portkey suits teams building or operating applications that use multiple AI models and need routing, activity monitoring, and prompt management.
12
Haystack
APISelf-hosted Free plan Record4.6 Visit Haystack is aimed at AI developers and engineers building modular, transparent systems.
13
PromptLayer
WebAPISelf-hosted $49 a month Record4.6 Visit PromptLayer suits engineers and domain experts who need to manage prompts, evaluate changes, and observe AI product activity together.
14
LiteLLM
WebAPISelf-hosted Free plan Record4.5 Visit LiteLLM suits platform teams that need a shared API for multiple model providers and controls for usage, routing, and spend.
15
Arize Phoenix
WebAPISelf-hosted Free plan Record4.4 Visit Phoenix suits teams that need to inspect AI application traces and compare evaluation results across versions.
Before you choose
Review pricing options
Check whether a tool offers a free plan, a free trial or paid access. Braintrust pairs a free plan with paid access from $249 per month; Helicone combines a free plan and a 7-day trial with paid access from $79 per month.
Cohere North lists pricing on request, so confirm the cost before choosing it.
Match the deployment model
Review where a tool runs before adopting it. Available environments listed here include API, web, self-hosted, Linux, macOS and Windows.
Cohere North supports self-hosted and web use. Fireworks AI can run through its API, on a self-hosted setup or on the web.
Check model and workflow support
Compare the LLM providers a tool supports, along with its SDK languages. These details affect how it connects to your models and code.
Use LLM evaluation capabilities to measure outputs, and LLM observability capabilities to monitor application behavior.
Review open-source status
Open-source code can matter when you need to inspect or change a tool. DSPy and Haystack identify themselves as open source.
Check the licence and deployment terms for the tool you plan to use.
Questions
Which listed tools show a free plan?
The records mark Arize Phoenix, AutoGen, Braintrust, CrewAI AMP, DeepEval, DSPy, Google Gemini API, GroqCloud, Haystack and Helicone as offering free plans.
Which tool lists a free trial?
Helicone offers a 7-day trial, plus a free plan and paid access starting at $79 per month.
Which tools are open source?
DSPy and Haystack list open source in their pricing notes, and each also indicates a free plan.
Can these tools run self-hosted?
Self-hosted is one of the listed platforms. Cohere North and Fireworks AI both show support for it in the records.
Which tool lists paid access from $249 per month?
Braintrust lists a free plan and paid access starting at $249 per month.
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