harmonic-tx-sender

Leader-targeted Solana transaction sender.

Build

cargo build --release

Binary lands at ./target/release/harmonic-tx-sender.

Setup

1. Generate and fund a keypairs directory

The sender rotates through a directory of payer keypairs. Each keypair pays its own base fees and priority fees.

Generate:

mkdir keypairs
for i in $(seq 1 $NUM_KEYPAIRS); do
  solana-keygen new -s --no-bip39-passphrase -o "keypairs/k${i}.json"
done

Fund — either by airdrop on testnet:

for f in keypairs/*.json; do
  solana airdrop -k "$f" 1 -u testnet
done

or by transferring from an already-funded keypair:

FUNDER=/path/to/funder.json
for f in keypairs/*.json; do
  solana transfer "$(solana-keygen pubkey "$f")" 1 \
    -u testnet --from "$FUNDER" --fee-payer "$FUNDER" --allow-unfunded-recipient
done

Each tx pays a 5000-lamport base fee plus a per-CU priority fee that runs from a few thousand up to ~15K lamports depending on the recipe.

2. Write a config

Edit or copy config/example.toml. At minimum, set:

• rpc_url — any Solana RPC for blockhash + leader-schedule queries
• keypairs — path to the directory you just populated
• identity — base58 pubkey of the validator you want to target
• target_tps — sustained tx rate

and exactly one of the following delivery paths:

• tpu_addr — direct QUIC to a specific validator TPU socket
• block_engine_url — Harmonic bundles
• jito_url — Jito bundles via Jito's public block engine

3. (Block engine only) Whitelist your searcher key

Using block_engine_url requires that the keypair authenticating with the block engine is whitelisted. By default that's the first keypair in your keypairs/ directory; override with harmonic_bundle_keypair to point at a dedicated searcher key.

Get the pubkey:

solana-keygen pubkey keypairs/k1.json

Then contact the Harmonic team with that pubkey to be whitelisted. Without whitelisting, auth fails immediately with Pubkey not whitelisted for role.

Run

./target/release/harmonic-tx-sender <config.toml>

The process runs until killed with Ctrl-C.