Guide · 2026
Best Agent & Prompt Frameworks (2026)
The 10 most complete agent & prompt frameworks listings on Prompt Junky, ranked by how much verified public information each publishes: description, services, pricing, and a live website. 66 are listed in this category. Order is not a quality rating, and no listing pays for its rank.
- 1
AdalFlow
A library for building LLM applications that also auto-tunes them, optimizing prompt text and few-shot demonstrations against a training set. It aims to make prompt tuning as routine as model training.
- Listed under Agent & Prompt Frameworks, Evaluation & Testing
- 4 services listed, including auto-optimized prompts, few-shot tuning, retriever and agent components
- Pricing published: Open source
- Serves the whole US
- 2
CrewAI
A Python framework for role-playing agent crews, where each agent is defined by a role, goal and backstory that become its prompt. Tasks are assigned to agents and executed sequentially or hierarchically.
- 4 services listed, including role-based agents, task delegation, crew orchestration
- Pricing published: Open source
- Serves the whole US
- 3
DSPy
A Python framework that replaces hand-written prompt strings with declarative modules and signatures, then compiles them against your data. Optimizers search for the wording and few-shot examples that score best on a metric you define.
- Listed under Agent & Prompt Frameworks, Evaluation & Testing
- 4 services listed, including declarative prompt modules, automatic prompt optimization, few-shot example search
- Pricing published: Open source
- Serves the whole US
- 4
EvoPrompt
The official implementation of a paper that applies evolutionary algorithms to prompt search, using a language model to perform crossover and mutation on candidate prompts. Populations are scored on a dev set each generation.
- 4 services listed, including evolutionary prompt search, genetic operators, benchmark tasks
- Pricing published: Open source
- Serves the whole US
- 5
GEPA
An optimizer that improves prompts and other text artifacts through reflective evolution, reading execution traces and natural-language feedback to propose edits. It integrates with DSPy and other pipelines.
- Listed under Agent & Prompt Frameworks, Evaluation & Testing
- 4 services listed, including reflective prompt evolution, trace-driven feedback, pareto candidate selection
- Pricing published: Open source
- Serves the whole US
- 6
Guidance
A templating language for steering language models token by token, interleaving generation with control flow, regex and grammar constraints. Output structure is enforced during decoding rather than checked afterwards.
- Listed under Agent & Prompt Frameworks, Prompt Managers & Versioning
- 4 services listed, including constrained generation, templating language, regex and grammar control
- Pricing published: Open source
- Serves the whole US
- 7
Haystack
deepset's orchestration framework for retrieval and agent pipelines built from composable components. Prompt builders are pipeline nodes, so prompt text is versioned with the rest of the pipeline definition.
- Listed under Agent & Prompt Frameworks, Evaluation & Testing
- 4 services listed, including composable pipelines, prompt builder components, rag orchestration
- Pricing published: Open source
- Serves the whole US
- 8
Instructor
A library that maps model responses onto Pydantic models so a prompt returns validated typed objects instead of raw text. Failed validations are automatically retried with the error fed back into the prompt.
- 4 services listed, including pydantic-typed outputs, automatic retries, validation feedback loop
- Pricing published: Open source
- Serves the whole US
- 9
LangChain
One of the most widely used frameworks for LLM applications, providing prompt templates, chat message abstractions, tool calling and agent loops. It connects to the LangSmith platform for tracing and prompt management.
- Listed under Agent & Prompt Frameworks, Prompt Managers & Versioning
- 4 services listed, including prompt templates, agent loops, tool integrations
- Pricing published: Open source
- Serves the whole US
- 10
Letta
A platform for stateful agents, formerly MemGPT, where the agent manages its own context window through editable memory blocks. The prompt is assembled from persistent memory rather than rebuilt each turn.
- Listed under Agent & Prompt Frameworks, Prompt Managers & Versioning
- 4 services listed, including self-editing memory, stateful agents, context management
- Pricing published: Open source
- Serves the whole US