voitta-bookmarklet is a lightweight browser-side entry point for a larger local AI tool runtime. The user enters the bookmark URL, clicks it on any HTTPS page, and gets a right-side chat pane injected into the current document. That pane is backed by a local FastAPI service running on https://127.0.0.1:12358, which serves both the frontend widget and the tool-using chat backend.

The interesting part is not the bookmarklet itself; it’s the architecture behind it. The frontend is built as a single bundled widget and mounted via Shadow DOM, which keeps the UI isolated from page styles. The backend exposes a multi-provider chat runtime supporting Anthropic, OpenAI, and Gemini, plus an in-memory tool bridge for orchestrating tool calls, session state, and provider-specific actions.

The repository is structured around extensibility. There is a clear separation between provider-agnostic tools, provider-specific integrations, browser/page-context tooling, and retrieval components. External data providers live under their own packages, with Google Drive implemented first via OAuth and read-only access. The project also includes RAG indexing for its own documentation, so the agent can use repo-specific reference material as part of its runtime behavior.

From an engineering perspective, this is a practical approach to embedding an assistant into real browser workflows without requiring a full browser extension as the primary product surface. It treats the browser page as the host environment, the local backend as the secure execution boundary, and the model as one component inside a broader tool system.

The implementation also surfaces the real constraints of this design: local TLS setup, CSP restrictions on script injection, OAuth plumbing, and the need to separate user-facing widget code from backend orchestration logic. Those details are exactly what turn a generic “AI chat overlay” into an actual usable system.

In short, voitta-bookmarklet is interesting because it is not just a UI experiment. It is a compact architecture for attaching model-driven, tool-using assistance to arbitrary web pages while keeping execution local and leaving room for more integrations over time.

Repo so you can give a star: https://github.com/voitta-ai/voitta-bookmarklet