18.7
Vellum describes itself as a personal AI assistant that can read files, manage calendars, send email, run code, and control a computer.
Free planOpen sourceAndroidiOSWeb
Best LLM Application Development Frameworks in 2026
LLM application frameworks provide building blocks for software that uses language models. Typical coverage includes retrieval-augmented generation (RAG), agents with tools, workflow graphs, and ways to optimize prompts. Look at free plans, entry-level paid prices, primary language, open-source licensing, and JavaScript or TypeScript SDK support. Check whether the framework runs where you work: Linux, Windows,…
28.3
Scanopy is network discovery and documentation software for mapping hosts, services, and network connections.
Free planOpen sourceWebAPILinux
37.2
Flowise is an open-source platform for building generative AI agents and workflows based on large language models.
Free planWebAPILinux
- 4
LlamaIndex
LlamaIndex helps developers and enterprises process documents and build AI workflows around them.
Free planWebAPILinuxSelf-hosted7.1From $50 a month - 5
Vercel
Vercel is infrastructure for building, deploying, securing, observing, and scaling apps and agents.
Free planWebAPI7.0$20 usage-based - 6
LangChain
LangChain is a free, open-source framework for building agents that connect models with tools.
Free planAPISelf-hosted6.8$39 usage-based - 7
OpenRAG
OpenRAG is a free, AGPL-3.0 modular framework for building document-grounded retrieval-augmented generation systems.
Free planWebAPISelf-hosted6.7Free plan - 8
txtai
txtai is an open-source framework for semantic search, language-model orchestration, and language-model workflows.
Free planAPILinuxmacOSSelf-hosted6.7Free plan - 9
CrewAI AMP
Free planWebAPISelf-hosted6.4Free plan - 10
Haystack
Haystack is an open-source AI orchestration framework for developers building agents, multimodal applications, advanced retrieval-augmented…
Free planAPISelf-hosted6.4Free plan - 11
Langflow
Langflow is a free, open-source Python framework for building customizable AI applications, including agent and MCP applications.
WebAPILinuxmacOS6.2 - 12
Pathway Live Data Framework
Pathway Live Data Framework is a Python framework for building analytics and AI data pipelines over stored data and live streams.
Free planAPISelf-hosted6.1Free plan - 13
DSPy
DSPy is a free, MIT-licensed, open-source Python framework for building AI programs and systems.
APISelf-hosted5.7 - 14
AgentScope
WebLinuxmacOSWindows5.0 - 15
Genkit
WebLinuxmacOSWindows5.0 - 16
Letta
WebLinuxmacOSWindows5.0 - 17
LMQL
WebLinuxmacOSWindows5.0 - 18
AutoGen
LinuxmacOSWindows4.9 - 19
AWS Strands Agents
LinuxmacOSWindows4.9 - 20
NVIDIA NeMo Guardrails
LinuxmacOSWindows4.9 - 21
Apache Burr
LinuxmacOSWindows4.7 - 22
LangChain4j
LinuxmacOSWindows4.7 - 23
Langroid
LinuxmacOSWindows4.7 - 24
Mastra
Web4.7 - 25
Microsoft GraphRAG
LinuxmacOSWindows4.7
Choosing well
Check where it runs
Frameworks on this list can target Linux, Windows, macOS, the web, an API, or self-hosted deployment. Match those options to your development machine and deployment plan.
Android is not shown in the platform facts. If you need to work from a Xiaomi, Redmi, or POCO phone, confirm that the framework's web or API workflow is usable there.
Start with the plan details
A free plan can help you begin without a subscription. Freemium entries can add paid levels; Agno notes service from $150 per month with a 14-day trial, and Flowise notes service from $35 per month.
Read the pricing note for limits and trial terms before moving a project beyond its free plan.
Match the development features
Assess whether each framework supports RAG, agent and tool use, workflow graphs, and prompt optimization. These capabilities shape how you connect model calls, data, tools, and repeatable steps.
When fitting a framework to an existing codebase, consider its main language and whether it has a JavaScript or TypeScript SDK.
Review the code licence
Several listed projects provide open-source code, and some are explicitly described as open source. Check the specific open-source licence and its terms before changing or distributing code.
A free plan and an open-source licence are separate considerations, so review both for the framework you select.
Questions people ask
Do these frameworks have free plans?
Projects on this list offer free plans. Some use freemium pricing, so check each pricing note for limits and paid tiers.
Which features should I compare?
Look at RAG support, agent and tool use, workflow graphs, prompt optimization, primary language, and JavaScript or TypeScript SDK support.
Are the frameworks open source?
Projects on this list provide open-source code. Check the specific project's open-source licence before modifying or distributing its code.
Are trials available?
Projects on this list include a free trial. Agno's pricing note lists a 14-day trial; trial terms can differ by project.