OmniChat: A Zero-Backend AI Chat PWA with Local AES-GCM Encryption

Description and use

OmniChat is a zero‑backend PWA that encrypts LLM API keys with AES‑GCM in IndexedDB, enabling privacy‑focused, client‑side AI chat across multiple providers.

Problem

Users want to test multiple LLM providers without exposing their API keys or chat logs to third‑party servers.

Outcome

OmniChat enables privacy‑centric AI chat by keeping all keys and logs client‑side, supporting multiple providers, and offering offline functionality.

Workflow

• 1. Install OmniChat via the GitHub repo or use the live demo.
• 2. Enter API keys for desired LLM providers; keys are encrypted with AES‑GCM and saved to IndexedDB.
• 3. Select providers (Gemini, Groq, Anthropic, etc.) and send messages; requests go directly from the browser.
• 4. View responses side‑by‑side for comparison.
• 5. Store reusable prompts in the local Prompt Vault.
• 6. Work offline thanks to the PWA service worker cache.

Evidence

All API keys are securely encrypted and stored locally in the browser's IndexedDB using AES‑GCM.

Source

The application is entirely client-side. It is built as a Progressive Web App (PWA) using React, TypeScript, and Vite.

Source