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📖 The AI Tool Bible

Google Agent Development Kit (ADK) vs Stagehand

A side-by-side look at pricing, capabilities, pros, cons, and our editorial scores.

 
Google Agent Development Kit (ADK)
Agents
Stagehand
Agents
TaglineGoogle's open-source framework for building, evaluating, and deploying production AI agentsThe SDK for browser agents
CategoryAgentsAgents
PricingFree· Framework itself is free and open-source (Apache 2.0). Costs come from the underlying model provider (e.g. Gemini API / Vertex AI usage) and any hosting infrastructure (Cloud Run, GKE, Agent Engine).Freemium· SDK is free/open-source (MIT). Runs locally against any LLM API key. Optional Browserbase cloud runtime: Free $0/mo, Developer $20/mo, Startup $99/mo, Scale custom.
ModelGemini (default) plus Claude, GPT-4/5, Llama, and other providers via LiteLLMModel-agnostic (OpenAI GPT-4o, Anthropic Claude, Google Gemini via Vercel AI SDK)
Editorial score
Use cases
Multi-agent research assistantCustomer support triage agentRAG chatbot backed by Vertex AI SearchCode review and refactoring agentBigQuery natural-language analytics agentDocument processing pipelineVoice/streaming conversational agentInternal tool-use agent orchestrating APIsEvaluation and regression testing of LLM workflowsEnterprise workflow automation on Agent Engine
AI web scrapingAutonomous browser agentsEnd-to-end UI testingStructured data extractionForm-filling automationCompetitor price monitoringRPA replacementQA regression suitesMulti-step research agentsBooking and checkout automation
Pros
  • Genuinely open-source (Apache 2.0) with active Google engineering behind it, not a hosted-only product
  • Multi-language: first-class Python, Java, and Go SDKs — rare among agent frameworks that are usually Python-only
  • Built-in dev UI (`adk web`) with trace inspection, event stream, and session replay speeds up debugging enormously
  • Model-agnostic via LiteLLM — Gemini is default but Claude, GPT, and local models plug in cleanly
  • Rich multi-agent primitives out of the box: SequentialAgent, ParallelAgent, LoopAgent, and hierarchical sub-agents
  • Tight Google Cloud integration for deployment (Cloud Run, GKE, Agent Engine) plus native BigQuery/Vertex Search tools
  • Evaluation harness with trajectory-level scoring is included, not a separate paid add-on
  • First-class MCP (Model Context Protocol) client and server support
  • Open-source (MIT) and built directly on Playwright, so you never lose escape-hatch access to the raw page, frame, and network APIs
  • Natural-language act/extract/observe primitives eliminate most brittle selectors and dramatically reduce maintenance when target sites change
  • Zod-schema extraction returns typed, validated data instead of loose JSON, which fits cleanly into typed backends
  • Model-agnostic via the Vercel AI SDK — swap OpenAI, Anthropic, Gemini, or a self-hosted model without rewriting the agent
  • Optional Browserbase cloud provides stealth browsers, residential proxies, session replay, and captcha handling out of the box
  • TypeScript and Python SDKs with good docs, a growing example library, and an active Discord
  • observe() lets you inspect proposed actions before executing, which makes debugging and human-in-the-loop review practical
Cons
  • Documentation and examples lean heavily on Gemini + Google Cloud; non-Google paths work but feel like second-class citizens
  • API surface is still evolving — breaking changes between minor versions have been common through 2025-2026
  • Multi-agent orchestration primitives are powerful but the graph/callback model has a real learning curve compared to a plain prompt loop
  • Agent Engine deployment is convenient but locks you into GCP billing and quotas
  • TypeScript/Kotlin support lags the Python SDK in features and community examples
  • Every act/extract call issues an LLM request, so token costs and latency add up fast on large crawls compared with hand-written Playwright
  • Non-deterministic by nature — the same prompt can occasionally pick a different element, so critical flows still need assertions and retries
  • Cloud features (stealth, proxies, captcha) require a paid Browserbase plan; running purely local means you handle those problems yourself
  • Still a young project — API surface and best practices are evolving and breaking changes appear between minor versions
  • Requires developer skills (Node/TS or Python) — no visual builder for non-technical automators
Websitegoogle.github.iostagehand.dev
Pick Google Agent Development Kit (ADK) if
  • Genuinely open-source (Apache 2.0) with active Google engineering behind it, not a hosted-only product
  • Multi-language: first-class Python, Java, and Go SDKs — rare among agent frameworks that are usually Python-only
  • Built-in dev UI (`adk web`) with trace inspection, event stream, and session replay speeds up debugging enormously
  • Model-agnostic via LiteLLM — Gemini is default but Claude, GPT, and local models plug in cleanly
Pick Stagehand if
  • Open-source (MIT) and built directly on Playwright, so you never lose escape-hatch access to the raw page, frame, and network APIs
  • Natural-language act/extract/observe primitives eliminate most brittle selectors and dramatically reduce maintenance when target sites change
  • Zod-schema extraction returns typed, validated data instead of loose JSON, which fits cleanly into typed backends
  • Model-agnostic via the Vercel AI SDK — swap OpenAI, Anthropic, Gemini, or a self-hosted model without rewriting the agent