Introduction
KiiChain Pay is non-custodial payments and FX infrastructure. Move money across on-chain and off-chain rails — FX, DEX swaps, on-ramps and off-ramps — through a single API.
KiiChain Pay (formerly KiiEx) is the payments and foreign-exchange layer of the Kii ecosystem. It lets you move value between fiat and crypto, run FX and DEX swaps, and operate on-ramps and off-ramps — mixing on-chain and off-chain operations behind one programmatic interface.
Every KYC-verified account gets its own embedded crypto Kii Wallet whose keys are held by our wallet provider and owned by the user, never by KiiChain Pay. To automate on-chain operations from a Kii Wallet, the user grants the platform an explicit delegation to sign on its behalf.
The KiiChain Pay web app lives at https://pay.kiichain.io. This documentation is mainly aimed at API usage. You'll generate API keys, delegate your wallet, and drive FX, ramps and swaps from your own backend.
Core concepts
Non-custodial by design
Users transact from a non-custodial wallet — the embedded Kii Wallet (keys managed by Privy, owned by the user) or their own external wallet. KiiChain Pay never holds a private key.
Internal wallets (Kii Wallet)
Optional. A convenience embedded wallet — one per account, per supported chain (EVM, Cosmos, Solana, Tron, Bitcoin), with sponsored gas and no key management. Users can bring their own external wallet instead; on-ramps, off-ramps and FX swaps work the same either way. Provisioned automatically once KYC is approved. See Internal wallets.
Delegated access
A user delegates their Kii Wallet to the platform's signer so you can sign and broadcast transactions server-side — no per-transaction signing prompt. See Privy delegated access.
On-chain + off-chain
Crypto balances live on-chain in the user's wallet (Kii or external); fiat and reserved balances are tracked in KiiChain Pay's internal double-entry ledger (available / locked).
KYC-gated
Kii Wallets, fiat rails, limits and provider access unlock through KYC. DEX swaps from an external wallet need no KYC. See KYC.
API keys
Every authenticated API call carries an API key; write calls are additionally signed. See Generating API keys.
Permissionless DEX
DEX swaps run on-chain directly from any external wallet — no account, KYC or authenticated user required, and no activity is recorded.
How the pieces fit together
Crypto moves on-chain through the user's wallet — a Kii Wallet or their own external wallet; fiat moves through provider rails (on-ramps, off-ramps, virtual accounts); and KiiChain Pay keeps both sides reconciled in its internal ledger.
The integration journey
Setup is dashboard-first: a few one-time steps in pay.kiichain.io unlock the API for everything that follows.
Sign up for a KiiChain Pay account at pay.kiichain.io.
Complete KYC — choose individual or company. This sets your account level and limits. See KYC.
Kii Wallets are provisioned automatically the moment KYC is approved — one per supported chain. See Internal wallets.
Delegate your Kii Wallet so the platform can sign wallet operations for you. See Privy delegated access.
Create an API key and store the secret. See Generating API keys.
Integrate — build on-ramps, off-ramps and FX swaps via the API. See the Guides and API Reference.
Using your own external wallet? You sign transactions yourself — skip delegation (step 4). (DEX swaps need none of this flow at all.)
Environments
KiiChain Pay exposes two environments. Point your integration at the matching API base URL:
Production
https://pay.kiichain.io
https://backend.pay.kiichain.io
Staging
https://pay.staging.kiichain.io
https://backend.pay.staging.kiichain.io
All REST endpoints are versioned and namespaced by module — for example /users/v1/..., /accounts/v1/..., and /market/v1/....
Gas is on us. Every Kii Wallet operation is gas-sponsored by KiiChain Pay, so you don't need to hold native tokens to transact. Lean into it.
Next steps
Generating API keys — create a key and sign requests.
Internal wallets — understand the Kii Wallet model.
Privy delegated access — enable server-side signing.
KYC — levels, limits, and provider verification.
Last updated