Dowser vs Nanobrowser: your assistant's hands, or a second agent
2 September 2026 · 6 min read · by Akhil Gorantala
Nanobrowser is one of the most likeable projects in this space: open source, local-first, free, and genuinely clever about reliability. If you are choosing between it and Dowser, the two questions that decide it are who drives, and who pays per step.
What Nanobrowser is
A Chrome extension that runs its own multi-agent system, a Planner, a Navigator and a Validator, against whatever LLM API key you give it. You open its side panel, type a goal ("find me three flights under $300"), and the agents plan, act and check each other until it is done. It positions itself as an open alternative to OpenAI's Operator, and earns it: the multi-agent loop recovers well when pages misbehave, and everything runs in your browser with your key.
What Dowser is
Not an agent at all: a set of hands for the agent you already use. Claude Code, Cursor, Codex or any MCP assistant stays the brain, and Dowser gives it five tools (find, act, read, navigate, tabs) whose finding step runs on a local ranker in a few milliseconds, with no model call and no page content leaving your machine.
Side by side
| Nanobrowser | Dowser | |
|---|---|---|
| Who is the brain | Its own agent trio, in the extension | Your existing assistant, over MCP |
| Cost per step | LLM calls on your API key | No model call to find or click |
| Where you type | Its side panel | Wherever you already talk to your assistant |
| Page content | Goes to your chosen LLM API | Stays on your machine |
| Autonomy | Plans and self-corrects toward a goal | Does what your assistant asks, step by step |
| Price | Free, open source, plus your API usage | $29 once, 5-day trial |
The honest trade
Nanobrowser's autonomy is real: give it a fuzzy goal and its planner will grind at it. That costs API usage on every step and means trusting an agent loop with the wheel. Dowser trades autonomy for tightness: your assistant, the one that already knows your context and your repo, makes each decision, and the browser work itself is instant and free. For developer workflows, where the assistant is already open and the tasks are concrete, tight tends to win. For "go do this vague thing while I watch", Nanobrowser's loop is the better shape.
Questions people ask
Can they coexist? Yes, they are separate extensions. Just do not point both at the same tab at the same moment.
Is free plus API key cheaper than $29 once? Depends on volume. Occasional use, yes. Daily use inverts it: model-driven steps meter forever, a local ranker does not. The full tool comparison works through the economics.
Does Dowser have a side panel or its own chat? No, by design. Your assistant is the interface; Dowser only adds the hands and a visible cursor.
Keep your assistant as the brain and make the browser work free per step: Dowser, 5-day trial, $29 once. Get Dowser.