wisp-esp32

A minimal Nostr relay for ESP32-S3.

Overview

Wisp-ESP32 is an ephemeral Nostr relay that runs on $10 hardware. Your relay, your rules, your data—and it cleans up after itself.

Why run your own embedded relay?

• Privacy: Events never touch third-party infrastructure
• Sovereignty: Works offline, no cloud dependency
• Ephemeral by design: 21-day TTL means data automatically disappears
• Edge-ready: Building block for mesh networks and air-gapped setups

Use Cases

Local Relay for FROST Signing Ceremonies

Wisp pairs with keep-esp32 for private threshold signing coordination. Instead of leaking signing activity to public relays:

┌─────────────┐     ┌─────────────┐     ┌─────────────┐
│  Keep #1    │     │   Wisp      │     │  Keep #2    │
│  (signer)   │◄───►│  (relay)    │◄───►│  (signer)   │
└─────────────┘     └─────────────┘     └─────────────┘
                          ▲
                          │
                    ┌─────────────┐
                    │ Coordinator │
                    │    (CLI)    │
                    └─────────────┘

• DKG ceremony events stay local
• Signing coordination never hits public relays
• 21-day TTL auto-purges ceremony artifacts

Family/Small Group Relay

5-10 connections is perfect for a household or small community running their own infrastructure without a VPS.

Mesh Networking Node

Unlike stateless mesh relays, Wisp provides ephemeral-but-persistent storage—nodes can query recent history while data still auto-expires.

Specs

Resource	Value
Connections	5-10 concurrent WebSocket
Storage	5,000 events
TTL	21 days
Crypto	Schnorr via libnostr-c/noscrypt

Supported NIPs:

• NIP-01 (protocol)
• NIP-09 (deletion)
• NIP-11 (relay info)
• NIP-40 (expiration)

Prerequisites

ESP-IDF v5.3.4

git clone -b v5.3.4 --recursive https://github.com/espressif/esp-idf.git
cd esp-idf && ./install.sh esp32s3
source export.sh

Clone repositories as siblings:

cd ~/projects  # or your preferred directory
git clone -b esp-idf-support https://github.com/privkeyio/secp256k1-frost
git clone https://github.com/privkeyio/wisp-esp32
git clone -b esp-idf-support https://github.com/privkeyio/noscrypt
git clone https://github.com/privkeyio/libnostr-c

Your directory structure should look like:

~/projects/
├── wisp-esp32/        # This repo
├── libnostr-c/        # Nostr library (symlinked in components/)
├── noscrypt/          # NIP-44 crypto (symlinked in components/)
└── secp256k1-frost/   # Schnorr signatures

Build

cd wisp-esp32
source ~/path/to/esp-idf/export.sh
idf.py build
idf.py -p /dev/ttyACM0 flash monitor

Hardware

• ESP32-S3 with 8MB Flash
• PSRAM optional (5000 event index with PSRAM, 1000 without)
• Tested on M5Stack CoreS3 Lite, ESP32-S3-DevKitC-1-N8R8
• AtomS3 Lite works but has limited PSRAM (reduced index capacity)

Testing

Hardware tests (requires device)

Requires: nak, websocat, curl, jq

# Install tools
go install github.com/fiatjaf/nak@latest  # or build from source
cargo install websocat
sudo apt install curl jq  # or brew install

# Run integration tests
RELAY=ws://<relay-ip>:4869 ./test/hardware/integration_test.sh

# Run stress tests
RELAY=ws://<relay-ip>:4869 ./test/hardware/stress_test.sh all

Native tests (no device)

cd test/native
mkdir -p ../../managed_components/espressif__cjson
git clone https://github.com/DaveGamble/cJSON.git ../../managed_components/espressif__cjson/cJSON
mkdir -p build && cd build
cmake .. && make
./test_router

License

MIT