Comparisons / Google ADK vs Haystack
Google ADK vs Haystack: Which Agent Framework to Use?
Google's Agent Development Kit (ADK) is an open-source framework for building multi-agent systems. Haystack by deepset is a framework for building NLP and LLM pipelines. Here is how they compare — paradigm, ecosystem, and the use cases each one is actually built for.
By the numbers
Google ADK
18.7k
3.2k
Python
Apache-2.0
2025-04-01
Google/Alphabet
Vertex AI
Yes
Haystack
24.7k
2.7k
Python
Apache-2.0
2019-11-14
deepset
GitHub stats as of April 2026. Stars indicate community interest, not necessarily quality or fit for your use case.
| Concept | Google ADK | Haystack |
|---|---|---|
| Agent | `LlmAgent` class with model, instructions, and `sub_agents` list | `Agent` component with `ChatGenerator`, tool definitions, and message routing |
| Tools | `FunctionTool`, built-in tools (Search, Code Exec), third-party integrations | `Tool` dataclass with function reference, name, description, parameters schema |
| Agent Loop | `Runner.run()` with automatic tool dispatch and sub-agent delegation | — |
| Multi-Agent | Hierarchical agent tree with root agent delegating to specialized sub-agents | — |
| Workflows | `SequentialAgent`, `ParallelAgent`, `LoopAgent` workflow primitives | — |
| Session | Session and State service with typed channels and persistence | — |
| Pipeline Architecture | — | `Pipeline()` with `add_component()` and `connect()` — a directed graph of typed components |
| RAG / Retrieval | — | `DocumentStore` + `Retriever` + `PromptBuilder` + `Generator` wired in a `Pipeline` |
| Memory | — | `ChatMessageStore` with `ConversationMemory` component in pipeline |
| Deployment | — | Pipeline YAML serialization, `Hayhooks` REST server |
Google ADK vs Haystack, head to head
Google ADK Google's Agent Development Kit (ADK) is an open-source framework for building multi-agent systems.
Haystack Haystack by deepset is a framework for building NLP and LLM pipelines.
Both wrap the same underlying agent pattern — an LLM call, a tool dispatch, a loop — in different abstractions. The choice between them is mostly about which mental model and ecosystem fits the team you have, not which one is technically more capable.
Pick Google ADK if
Pick Google ADK if aDK earns its complexity when you need multi-agent orchestration on Google Cloud with Vertex AI deployment. If you're using Gemini and need production-grade agent infrastructure, it's well-designed. For single-agent use cases or non-Google stacks, plain Python keeps things simpler. Google ADK is the right fit when the tradeoffs in its intro line up with how your team actually wants to work day-to-day; Haystack would force you to translate.
Pick Haystack if
Pick Haystack if haystack earns its complexity when you're building RAG pipelines with multiple retrieval stages, document processing, and production deployment needs. But for straightforward agents with a few tools, the plain Python version is simpler to write and debug. Haystack is the right fit when the tradeoffs in its intro line up with how your team actually wants to work day-to-day; Google ADK would force you to translate.
What both add
Both Google ADK and Haystack pull in a class hierarchy and a dependency tree to wrap what is, at the core, an HTTP POST in a while loop. If your use case is straightforward — one provider, a handful of tools, a single agent — the framework cost may exceed the framework benefit. The lesson below shows the same pattern in ~60 lines without either dependency.
Or build your own in 60 lines
Both Google ADK and Haystack implement the same 8 patterns. An agent is a function. Tools are a dict. The loop is a while loop. The whole thing composes in ~60 lines of Python.
No framework. No dependencies. No opinions. Just the code.
Build it from scratch →