Build on TxFlow: Builder Codes, API and What to Ship
TxFlow builder codes pay up to 0.1% on perps and 1% on prediction markets. How the API works, mainnet access and what founders should build.
Build on TxFlow: Builder Codes, the API and What to Ship
Short answer: TxFlow builder codes let any frontend, bot or wallet that routes orders to TxFlow charge its own fee, up to 0.1% on perps and 1% on prediction (outcome) markets, settled on-chain. The Builder API is documented with a public testnet today. On mainnet, builder codes are in a limited access phase: you apply for a developer slot at txflow.com/apply. As of October 2026, that is an early window for founders.
Updated October 23, 2026, from TxFlow's Builder Code and API docs.
> "A builder code turns order flow into revenue without a partnership deal. You sign, you route, you claim."
What is a TxFlow builder code?
A TxFlow builder code is an on-chain fee you attach to orders you submit for your users. There is no revenue-share contract, no off-chain accounting and no payout rail. It works in three steps:
builder object with your address and a fee within that cap.claimBuilderRewards action, whenever you like.The fee is per order, so you can price different products differently. It is charged on top of the user's normal TxFlow fee, so the user sees the sum.
What are the limits?
Builder fees are capped at 0.1% on perps and 1% on outcome markets, and your builder account must hold 100 USDC.
- Fee unit
fis tenths of a basis point:f = 100is 0.1%,f = 1000is 1%. - If the fee is over a cap, or the user never approved you, the fee is silently ignored and the order still fills. Watch
builderStateto see if you are actually accruing. - Fees only accrue while your own perp account holds at least 100 USDC.
- A user can approve up to 20 builders and can revoke you at any time.
- Spot is not covered: builder codes apply to perpetual and outcome markets only.
What does the API look like?
TxFlow's API is a signed-action exchange API with REST and WebSocket endpoints and no API keys. Reads need no auth; writes are signed locally (EIP-712 for account actions, an agent key for trading). Mainnet RPC is rpc.txflow.com, and the testnet ships a faucet so you can run the full builder flow for free. There are 23 WebSocket channels for market data and account updates. Rate limits are 50 reads and 10 writes per second per IP.
Builder code or Channel?
A builder code earns on flow into existing markets; a Channel lists its own markets. Channels are isolated venues on the TxFlow L1 where the operator sets markets, fees and liquidity. Probly, the prediction-market app, is the first partner Channel. Channels are onboarded case by case and the rules are still changing, so for most founders the builder code is the place to start.
What should you build?
Build where TxFlow's users already feel pain: points, hedging and prediction markets . My shortlist:
- A points copilot. Season 1 scores six dimensions with hidden weights. A dashboard that tracks a user's weekly volume, open interest , trading days and fees, and nudges them to stay consistent, is useful to every farmer. Route their trades through your builder code.
- A hedging terminal. One screen that opens a TxFlow perp and the opposite leg on another venue. Delta-neutral farmers need it and will pay a small fee for it.
- A prediction-market frontend. Outcome markets allow a 1% builder cap, ten times perps. A niche frontend (sports, a single league, crypto up/down) is a real business.
- A stock-perp app. TxFlow lists stock and FX perps. A simple "trade the Nasdaq after hours" interface for non-crypto users fits here.
- A Telegram trading bot . Approve once, trade from chat, earn on every fill.
Remember the Growth Reserve: TxFlow sets aside 488,000 points a month for campaigns and builder programs. Shipping early is how you get noticed for it.
How to start (step by step)
builderState.If you want to go from idea to deployed app fast, I built Deployr for exactly this: describe the tool, get a working app you can put in front of users.
Risks for builders
The main risks are limited mainnet access, a silent fee drop, and platform risk. Mainnet slots are not guaranteed. A misconfigured fee earns nothing without an error. The chain and its rules are young, and Channel rules are explicitly unstable. Keep your own record of each user's approved cap, because there is no API query for it.
TxFlow builder FAQ
How much can I earn with a TxFlow builder code? Up to 0.1% of perp notional and 1% on outcome markets, on top of TxFlow's own fee.
Do I need permission to use TxFlow builder codes? On mainnet, yes: apply for a developer slot. Testnet is open.
Does TxFlow have API keys? No. Writes are signed with your own keys, and reads need no auth.
Do builder codes work on spot? No. Perps and outcome markets only.
Related: TxFlow airdrop guide · TxFlow Points Season 1 · Perpl builder mPoints · Hotstuff builder perp DEX · No excuse to build
Join TxFlow:
Developer airdrops reward builders. Ship a real app and contract with Deployr, or cross over to ceoism, evolve into a founder, and go after grants and VC funding. Can't build it yourself? Deployr can build it for you.
More field notes
New to web3, or want the bigger picture beyond airdrops? Explore web3wikis - how it works, why it matters, and what you can do with it.
Research, not financial advice. Some links are referral links.