# Haystack vs Outlines — Fit & Features

Canonical: https://trutool.co/compare/haystack-vs-outlines
Author: Snehil (https://trutool.co/authors/snehil)

Compare Haystack and Outlines by use case, features, limitations, and evaluation questions.

## Compare fit, features, and limitations

### Haystack
Framework for retrieval-augmented generation and AI agent pipelines.
Best fit: Developers building and evaluating custom agents.
- Framework for retrieval-augmented generation and AI agent pipelines
Before you choose: Check licensing, maintenance status, supported providers, and hosting or inference costs.
Pricing: https://haystack.deepset.ai/
- [Read Haystack profile](https://trutool.co/tools/haystack): Read Haystack profile

### Outlines
Generate structured outputs from language models with schema constraints.
Best fit: Developers composing agents, structured model outputs, and tool workflows.
- Structured generation
- Schema constraints
- Model integrations
Before you choose: Check licensing, provider compatibility, maintenance, and tool permissions. Test failure recovery before enabling agent actions.
Pricing: https://dottxt-ai.github.io/outlines/latest/
- [Read Outlines profile](https://trutool.co/tools/outlines): Read Outlines profile