Payment schemes

Payment schemes define how payments are constructed, validated, and settled on blockchain networks. Kobaru currently supports the exact scheme on Solana, Base and SKALE.

Understanding payment schemes

A payment scheme specifies:

How the payment transaction is constructed

What validations occur before settlement

How settlement executes on-chain

Different schemes enable different payment patterns. The exact scheme performs a direct transfer of the specified amount.

Exact scheme

The exact scheme transfers tokens directly from the payer to your wallet. This is the simplest and most common payment pattern.

How it works

You specify the exact amount required for your API

The client constructs a transaction transferring that amount

Kobaru validates the transaction structure

Kobaru executes the settlement on-chain

Solana implementation

On Solana, the exact scheme uses SPL token TransferChecked instructions:

Transaction structure:
1. SetComputeUnitLimit (required)
2. SetComputeUnitPrice (required)
3. CreateAssociatedTokenAccount (optional, if destination ATA doesn't exist)
4. TransferChecked (required)

Key features:

Feature	Description
Direct transfer	Tokens go directly to your wallet
Gasless for clients	Kobaru pays transaction fees
Instant settlement	Sub-second finality on Solana
Exact amount	Transfer amount must match exactly

Payment requirements

When you use the exact scheme, your payment requirements look like:

{
  "scheme": "exact",
  "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
  "amount": "10000",
  "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
  "payTo": "YourWalletAddress...",
  "maxTimeoutSeconds": 60
}

Validation checks

Kobaru performs these validations before settling your payment:

Amount validation - Transfer amount exactly matches your requirements

Recipient validation - Destination is your correct associated token account

Fee payer validation - Kobaru is set as the fee payer

Instruction topology - Instructions are in the correct order

Priority fee limit - Fees do not exceed the configured maximum

Transaction simulation - Dry-run to ensure the transaction succeeds

Future schemes

Additional payment schemes are in development for different use cases:

Deferred scheme (planned)

Pre-authorize payments that you capture later. Useful for:

Metered usage billing

Subscription services

Variable-cost operations

Streaming scheme (planned)

Continuous micropayments for real-time services. Useful for:

Pay-per-second API access

Live data feeds

Compute time billing

Scheme selection

When you configure your integration, specify the scheme in your payment requirements:

Networks and assets - Supported blockchains and tokens

Usage models - Pay-per-request vs pay-per-time

API reference - Payment verification endpoint

Payment schemes

Understanding payment schemes#

Exact scheme#

How it works#

Solana implementation#

Payment requirements#

Validation checks#

Future schemes#

Deferred scheme (planned)#

Streaming scheme (planned)#

Scheme selection#

Related documentation#