Dowser vs Nanobrowser: your assistant's hands, or a second agent

2 September 2026 · 9 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, two questions decide it: who drives, and who pays per step. We build Dowser, so weigh the framing accordingly; the facts about Nanobrowser below come from its own documentation and repository.

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. A visible cursor shows every action, sensitive fields are refused, and low confidence returns candidates instead of clicking.

Side by side

The honest trade

Nanobrowser's autonomy is real: give it a fuzzy goal and its planner will grind at it, retrying and re-planning when a page fights back. 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. There is no dishonesty in either design; they are different answers to who should be driving.

The economics per step

A multi-agent loop reasons at every step: plan, act, validate, often re-plan. Each of those is an LLM call on your key, and a stubborn page multiplies them. Metered per-step costs are fine at low volume and painful at high volume, which is the same arithmetic as every snapshot tool, worked through with real numbers in the Playwright MCP post. Dowser's find-and-click path has no per-step meter at all; the only model spend is whatever your assistant was already doing to think. Occasional user: Nanobrowser's free wins. Daily user: the meterless path wins, usually within the first month.

Which fits which person

• Tinkerer who wants an open Operator at home: Nanobrowser, no contest.
• Developer living in Claude Code or Cursor: Dowser; the assistant you already trust stays the brain. Setup: the Claude Code guide or the Cursor guide.
• Privacy-first on sensitive dashboards: Dowser; page content stays local instead of flowing to an LLM API.
• Vague multi-step errands while you watch: Nanobrowser's planning loop.
• Unsure: both are cheap to try; Nanobrowser is free and Dowser's 5-day trial needs no card.

FAQ

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 $19 a month?

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 across the whole category.

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.

Can Nanobrowser be driven from Claude Code like an MCP tool?

That is not its shape; it is an agent with its own UI rather than a tool surface for other assistants. If MCP-driven hands are what you want, that is exactly the Dowser and Browser MCP category.

Which handles logins and sessions better?

Both act in your real browser, so both inherit your logins equally. The difference is downstream: what each does with page content after reading it.

Is Dowser's code auditable like Nanobrowser's?

Nanobrowser is fully open source. Dowser is commercial; the store-distributed build is unobfuscated and reviewable in the Chrome Web Store's source viewer, and the extension's network surface is one local WebSocket to 127.0.0.1, which you can verify from its manifest and traffic.