Capsule

Capsule launched in San Francisco around 2022 with a straightforward goal: make blockchain interaction as easy to integrate as any other web service. The company has since rebranded to Para (getpara.com), but the product line is continuous—an embedded wallet SDK powered by distributed multi-party computation (MPC) and passkeys, built so that any application can offer its users a self-custodial wallet without seed phrases, browser extensions, or a detour through a separate crypto onboarding flow.

The Problem

Most crypto applications still force users through a disjointed flow: install a wallet extension, back up a seed phrase, fund a fresh address, then navigate back to the original app. Each step loses a portion of would-be users. Capsule replaces that flow with authentication methods people already use—email, phone, social login, or biometric passkey—while preserving genuine non-custody, so neither the developer nor Capsule ever holds a complete private key.

How It Works

Capsule's security foundation is a threshold MPC scheme combined with device-native passkeys. When a user creates a wallet, the private key is never generated or stored in complete form anywhere. Instead, cryptographic key shares are split between the user's device (protected by the device's secure enclave, gated behind biometrics or a PIN) and Capsule's server-side infrastructure. Signing a transaction requires both parties to contribute via threshold cryptography. Even if a user's email account is compromised, an attacker cannot extract the wallet—the device enclave holds the essential second share.

Key refresh and rotation are built into the protocol. Key shares can be updated periodically without changing the wallet address, limiting long-term exposure from any single share. The design is chain-agnostic at the MPC layer, with chain-specific signing adapters (ECDSA for EVM, Ed25519 for Solana, and so on) layered on top.

Products and Developer Tooling

Capsule/Para offers three primary integration paths:

• Para Modal: A pre-built React component that handles the full authentication UI, wallet creation, and session management. Developers drop it into a web app and get a working embedded wallet flow immediately.
• Custom UI (Headless SDK): Hooks and primitives for teams that want to design their own interface while using Capsule's key management and signing backend underneath.
• Backend API: A REST API for server-side integrations where the application backend manages authentication and signing on behalf of users.

Beyond the core wallet, the platform ships:

• Policy engine: Programmable spending limits, progressive two-factor requirements, and automated transaction approvals—useful for compliance-sensitive applications and for scoping what each integrated application is permitted to do with a user's wallet.
• Account abstraction: Smart contract wallet support and gas sponsorship, enabling applications to pay transaction fees on behalf of their users.
• Multisig: Multiple required signers for institutional or team use cases.
• On/off ramps and token movement: Built-in send, bridge, and swap so users can move assets without leaving the host application.
• Full white-labeling: The SDK can be branded entirely as the host product, with no visible Capsule attribution.

SDK coverage spans React, Next.js, Vue, Svelte, React Native, Expo, Flutter, Swift (iOS), and Node.js, as well as Telegram bots and Chrome extensions.

Solana Integration

Capsule added MPC-powered Solana wallets in mid-2025. The integration applies the same distributed key architecture to Solana's Ed25519 signing scheme, giving Solana developers the identical passkey-secured, no-seed-phrase experience already available on EVM chains. Web and mobile SDKs are available, and the launch targeted consumer Solana applications—AMMs, trading interfaces, and onchain games—where the ecosystem's emphasis on user experience makes embedded wallets a natural fit. Gas sponsorship and the policy engine work for Solana transactions alongside their EVM equivalents.

The full supported network list runs to 18+ chains: Ethereum and major L2s (Base, Optimism, Arbitrum, Polygon, Linea), Solana, Cosmos, Stellar, Avalanche, Sei, and Celo among them.

Cross-Application Portability

One of Capsule's more distinctive design choices is the universal wallet: a wallet created inside one application is portable to any other application that also integrates Capsule. Users carry their existing address and balance across the ecosystem without re-funding or re-registering. Per-app permission controls determine what each application can do with the shared wallet, so portability does not mean a single app can access funds held by another. This positions Capsule differently from embedded wallet providers that create isolated, per-app key pairs.

Security and Compliance

Least Authority, a cryptographic security firm, audited Capsule's MPC implementation in both October 2023 and January 2024. In January 2025, the company earned SOC 2 Type II certification, meeting the operational security standard required by enterprise customers in regulated industries.

Team and Traction

CEO Nitya Subramanian co-founded Capsule Labs, Inc. after participating in a16z Crypto's Startup School. The platform has grown to serve more than 10 million users across over 100 developer organizations. Notable integrations include the Ethereum Foundation, ENS, MetaMask, Vana, Eco, ElizaOS, and Juicebox. Subramanian has more recently spoken publicly about the company's roadmap toward agent wallets—programmable signing permissions designed for AI agents operating autonomously on-chain—a direction that leverages the existing MPC policy engine.

Rebrand Note

In early 2025, Capsule announced a rebrand to Para. The usecapsule.com domain now redirects to getpara.com. The product, team, and technical architecture are continuous with the original Capsule; the rename reflects a broadening of scope toward a fuller payment and authentication infrastructure suite beyond embedded wallets alone.