web3auth

name: web3auth description: Integrates MetaMask Embedded Wallets (Web3Auth) for non-custodial wallets via social login or custom JWT (Firebase, Auth0, Cognito). Use when integrating @web3auth/modal (React, Vue, Next.js, Vite, Angular), @web3auth/react-native-sdk (Expo/bare RN—Custom Dev Client, not Expo Go), web3auth_flutter, native Android/iOS, Unity, or @web3auth/node-sdk. Invoke for Sapphire devnet/mainnet, dashboard client ID, grouped connections (same address across Google + email passwordless), implicit vs JWT auth flows, useWeb3AuthConnect, id_token server-side verification, or SDK migration (web v11, RN v9, OPENLOGIN_NETWORK/LOGIN_PROVIDER legacy). Also use when users get different wallet addresses per login method or need RN Metro setup/withWeb3Auth migration. Do NOT use for MetaMask browser extension only, RainbowKit/ConnectKit without embedded wallets, or unrelated smart-contract work.

MetaMask Embedded Wallets (Web3Auth)

Before writing code, use MCP tools for live docs and examples. Do not guess package names, API signatures, or config.

Dashboard: https://developer.metamask.io
Docs: https://docs.metamask.io/embedded-wallets/
Community: https://builder.metamask.io/c/embedded-wallets/5

MCP tools (use in order)

Examples and SDK source are live-discovered from GitHub. references/examples.md has filter recipes only. Always call get_example before codegen. MCP live at https://mcp.web3auth.io

1. search_docs — Search docs (Algolia) and example projects.
   • query (required)
   • platform?: react | vue | js | react-native | android | ios | flutter | unity | unreal | node
   • chain?: evm | solana | other
   • category?: quick-start | custom-auth | blockchain | feature | playground
2. get_doc — Full doc page by URL (docs.metamask.io). Read platform SDK doc before codegen.
3. get_example — Complete example source from GitHub (primary integration reference).
   • name?, platform?, chain?, category?, auth_method? (e.g. firebase, auth0, grouped)
   • Always fetch quick-start before a new integration; fetch auth-specific example for custom auth.
   • Check for filter recipes and eval anchor namesreferences/examples.md
4. search_community — Builder Hub. query? or topic_id? for full thread.
5. get_sdk_reference — SDK source for debugging types/signatures only (not feature discovery).
   • platform (required), module? (omit first to list modules), focus?: types | hooks | main-class | errors | all (default types)

MCP unavailable: https://docs.metamask.io/llms-embedded-wallets-full.txt (full), https://docs.metamask.io/llms-embedded-wallets.txt (index).

Prerequisite - Dashboard Setup flow

1. Create project at developer.metamask.io → Client ID.
2. Sapphire Devnet (local) or Mainnet (production).
3. Allowlist domains (web) or bundle IDs + deep link schemes (mobile).
4. Configure chains on Dashboard (web/Node) or in code (RN, Android, iOS, Flutter, Unity, Unreal).
5. Authentication: default socials or custom connections.
6. Optional: session duration, test accounts, key export, whitelabel.

Read https://docs.metamask.io/embedded-wallets/dashboard/

Key derivation rules (CRITICAL)

Same wallet address requires all of:

• Same Client ID
• Same Sapphire network (devnet or mainnet — never mix)
• Same connection configuration (same auth connection ID)
• Same useSFAKey boolean in integrations.

Change any → different address forever.

• Never change Client ID or Sapphire network in production.
• Sapphire is not blockchain devnet/mainnet. Devnet allows localhost; Mainnet does not.
• Local dev & staging: Sapphire Devnet. Production: Sapphire Mainnet only. Do not use Devnet in production.
• Avoid putting random flags like useSFAKey / useCoreKitKey — unless user already has it or wants to use wallet pregeneration. Wallet pregeneration only works with useSFAKey / useCoreKitKey as true.

SDK selection

Per-platform details and quirks: references/platforms.md

Scenarios

Fetch / tripwire / verify workflows by task: references/scenarios.md

Examples catalog [MOST IMPORTANT]

Examples are live on GitHub; call get_example or search_docs before writing integration code. MCP filter recipes and eval anchor names: references/examples.md

Authentication

Connections, implicit vs JWT flows, grouped connections, JWT iat rule: references/authentication.md

Migration

Upgrading existing integrations — version table, workflow, legacy PnP/CoreKit/SFA: references/migration.md

Summary: One guide per platform to current major (Web v11, RN v9, Android v9, iOS v10, Flutter v6). Use each guide's AI-assisted prompt. Never change Client ID or Sapphire network unless intentional.

• Migration index: https://docs.metamask.io/embedded-wallets/migration-guides/