nappletComposable Nostr apps

Sandboxed Nostr web applets that delegate signing, storage, and relay access to a host shell over the NIP-5D JSON envelope wire format.

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What are napplets?

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napplet.run

Single-purpose by design

A napplet does one thing well. The shell composes many sandboxed napplets instead of one monolithic client re-implementing feeds, DMs, profiles, and relay management.

Every request brokered

Napplets never call a signer, relay, or store directly. Every request is brokered through the shell over postMessage — to a remote signer, an extension, or the shell's own services. No window.nostr is installed.

Browser-enforced sandbox

The iframe uses allow-scripts only — no allow-same-origin. Identity is assigned at iframe creation via the unforgeable MessageEvent.source. No handshake required.

Modular NAP domains

Capabilities are split into NAP domains (relay, storage, inc, identity, and more). Shells implement the domains they support; napplets gate on domain presence.

Just a JSON envelope

Every message is { type: "domain.action", ...payload }. A simple, standardized wire format that any shell can host and any web app can speak.

Portable across shells

Build once against the protocol. Any compatible shell — like the Kehto reference runtime — can host your napplet without changes.