Run a prover server

The hosted Prover API is convenient, but you can run your own prover — for development, privacy, or control over proving costs. The prover is the charms-prover binary: the same code as the charms CLI, built with the prover feature, which enables real SP1 proving.

Build charms-prover

cargo install charms --locked --bin charms-prover --features prover

Run the server

charms-prover server                       # binds 0.0.0.0:17784
charms-prover server --ip 127.0.0.1 --port 17784

It exposes POST /spells/prove and GET /ready. Check readiness:

curl http://localhost:17784/ready          # -> OK

Point the charms CLI (or your client) at it:

export CHARMS_PROVE_API_URL=http://localhost:17784/spells/prove
charms spell prove …

Proving backends

The prover proves in two stages — the app/spell-checker proof, then a Groth16 wrapper — and two environment variables select the backend for each:

Variable	Values	Selects
APP_SP1_PROVER	cpu, network	The app + spell-checker proof.
SPELL_SP1_PROVER	app, network	The Groth16 wrapper. app reuses the app backend.

Prove with the SP1 Prover Network (recommended)

Generating real Groth16 proofs on CPU is slow; the Succinct Prover Network does it for you. Set both stages to use the network and provide your network key:

export APP_SP1_PROVER=network
export SPELL_SP1_PROVER=app          # the wrapper reuses the network app backend
export NETWORK_PRIVATE_KEY=0x…       # your Succinct Prover Network private key (required)
# optional — defaults to https://rpc.mainnet.succinct.xyz
# export NETWORK_RPC_URL=https://rpc.mainnet.succinct.xyz

charms-prover server

NETWORK_PRIVATE_KEY is required for network proving: the SP1 SDK looks it up when it builds the network prover, which happens on the first proof request. The server process starts without it, but the first prove will fail. It is the key for your Succinct account, which pays for proof requests.

Prove locally on CPU (no network)

Slow, but needs no account — useful for development:

export APP_SP1_PROVER=cpu
export SPELL_SP1_PROVER=app
charms-prover server

Optional configuration

Variable	Purpose
REDIS_URL	Cache proofs and deduplicate concurrent identical requests. Omit to disable.
CHARMS_FEE_SETTINGS	Path to a YAML file configuring the Charms protocol fee (addresses, rate).
SP1_GPU_SERVICE_URL	URL of a local SP1 GPU (Moongate) service, if proving on GPU.
RUST_LOG	Log level, e.g. info.

Note

For Bitcoin spells with Scroll outputs, a prover server is required (not mock mode): the server calls the Scrolls canister to fill in the Scroll output addresses while proving.