DSPy vs Prompt flow
Which should you use? A side-by-side look at what each one does, who it suits, what it costs, how hard it is to set up, and where each falls short.
Open source · MIT
A Python framework for building and optimizing language model programs instead of hand-writing prompts.
Open source · MIT
Open-source toolkit for building, testing, evaluating and deploying LLM apps, from prototype to production.
The short answer
Choose DSPy if you need…
- Python developers building LM-based pipelines such as RAG or multi-step agents
- Teams that want to improve prompts with measurable optimization instead of manual tweaking
- Researchers experimenting with prompt and weight optimization methods
- People who already have a way to measure output quality and want to tune against it
Choose Prompt flow if you need…
- Teams with existing Prompt flow applications that need to keep running until migration
- Developers who want to trace and evaluate LLM app behavior on datasets
- Engineers who want to run flow tests in CI/CD pipelines
- Developers who prefer a VS Code extension for visual flow editing
Side-by-side
| DSPy | Prompt flow | |
|---|---|---|
| Type | Library | Dev tool |
| Price | Free and open source | Free and open source |
| Licence | MIT | MIT |
| GitHub stars | 38.9k | 11.3k |
| Setup difficulty | Intermediate | Intermediate |
| How you get it | Install with a package manager | Install with a package manager |
| Platforms | API, Linux, macOS, Windows | — |
| Works with | OpenAI, Anthropic | — |
| Main language | Python | Python |
| Last code update | 4 days ago | 6 days ago |
What each one is
DSPy
DSPy is a Python framework for building AI systems out of modular code rather than long hand-written prompts. You describe what each step should do in Python, and DSPy provides algorithms to optimize the prompts and model weights behind those steps. The README says it is used for simple classifiers, RAG pipelines, and agent loops.
Prompt flow
Prompt flow is a set of development tools for building applications that use large language models (LLMs). You connect LLMs, prompts and Python code into a flow, then debug it, run it against larger datasets to evaluate quality, and deploy it. The README notes that Prompt flow is being retired by Microsoft on April 20, 2027, and is no longer recommended for new development.
Best for
DSPy
- Python developers building LM-based pipelines such as RAG or multi-step agents
- Teams that want to improve prompts with measurable optimization instead of manual tweaking
- Researchers experimenting with prompt and weight optimization methods
- People who already have a way to measure output quality and want to tune against it
Prompt flow
- Teams with existing Prompt flow applications that need to keep running until migration
- Developers who want to trace and evaluate LLM app behavior on datasets
- Engineers who want to run flow tests in CI/CD pipelines
- Developers who prefer a VS Code extension for visual flow editing
Strengths
DSPy
- Declarative Python code instead of brittle, hand-written prompt strings
- Includes optimization algorithms for prompts and weights, backed by published research
- Permissive MIT license with a large community (about 38.8k GitHub stars)
Prompt flow
- Covers the full cycle from prototyping through testing, evaluation and deployment in one toolkit
- Includes a VS Code extension and a command-line interface for flow development
- Released under the MIT license with an active public repository
Not ideal for
DSPy
- People who only need a one-off chat prompt; the framework adds structure that is unnecessary for simple use
- Non-Python users, since the README only shows Python code and pip installation
- Anyone wanting a no-code tool; the README describes a programming framework
Prompt flow
- Anyone starting a new project: the README says Prompt flow is no longer recommended for new development and suggests Microsoft Agent Framework instead
- Teams relying on Prompt flow runtime container images, which no longer receive security or package updates
- Non-developers, since setup uses the command line and a Python environment
Trade-offs
DSPy
- The README points to external docs for most details, so the top-level README gives limited hands-on guidance
- The README notes a recent LM integration change with breaking changes to provider options, so check the migration guide before upgrading
- Optimization benefits depend on having a sensible evaluation metric, which the README does not explain in detail
Prompt flow
- The README states retirement on April 20, 2027, and no new-development recommendation, so long-term support is limited
- Container images are no longer updated, which is a security concern for deployed workloads
- Setup and tutorials assume familiarity with Python and LLM API keys
Getting started
Prompt flow
Install the packages
pip install promptflow promptflow-toolsFrequently asked questions
What is the difference between DSPy and Prompt flow?
DSPy: A Python framework for building and optimizing language model programs instead of hand-writing prompts. Prompt flow: Open-source toolkit for building, testing, evaluating and deploying LLM apps, from prototype to production. DSPy suits python developers building lm-based pipelines such as rag or multi-step agents, while Prompt flow suits teams with existing prompt flow applications that need to keep running until migration.
Are DSPy and Prompt flow free?
DSPy: Free and open source. Prompt flow: Free and open source.
Is DSPy or Prompt flow more popular?
DSPy has more GitHub stars (38.9k) than Prompt flow (11.3k). Popularity isn't the same as fit — check which one matches your use case above.
What are other alternatives to DSPy and Prompt flow?
Other options people compare them with include LangChain, LlamaIndex, guidance, PromptPerfect, promptfoo.
Keep comparing
Built from our catalogue entries for both products: open-source details come from each project's README (AI-assisted, refreshed weekly) and GitHub data; AI-tool details are editorial. Spotted something wrong? Let us know from either product's page.