Kobaru
  1. Core Concepts
Kobaru
  • Kobaru.io Gateway API
    • Introduction
      • What is Kobaru?
      • Quick start
      • How x402 works
    • Integration
      • Standard x402 SDK
      • Advanced SDK
      • Transparent proxy integration
      • Direct API integration
    • Core Concepts
      • Available Chains and Assets
      • Payment schemes
      • Security
      • Usage models
    • Guides
      • Pricing your API
      • Going to Production
      • Testing with devnet
      • Bazaar discovery
    • API Reference
      • Error Handling
      • Get Supported Payment Kinds
      • Verify Payment Authorization
      • Settle Payment
    • Discovery
      • List Discovery Resources
    • Schemas
      • SupportedResponse
      • ErrorResponse
      • UnauthorizedResponse
      • RateLimitResponse
      • VerifySuccessResponse
      • VerifyErrorResponse
      • SettleSuccessResponse
      • SettleErrorResponse
      • DiscoveryResourceItem
      • ListDiscoveryResourcesResponse
  1. Core Concepts

Available Chains and Assets

This guide explains the blockchain networks supported by Kobaru Gateway, making it easy to choose the right one for your API.

Quick summary#

NetworkTypeBest ForGas Fees
SolanaHigh-performance L1Fast, low-cost paymentsGateway pays (for you)
BaseEthereum L2EVM ecosystem compatibilityGateway pays (for you)
SKALE on BaseApp-specific chainGasless, private transfersGateway pays (for you)
Good news: With all three networks, the gateway pays the gas fees. Your customers only pay the exact amount required for your service!

Solana#

What is Solana?#

Solana is a high-performance blockchain known for:
Very fast transactions (400ms confirmation)
Low fees (fractions of a cent)
Large ecosystem of tokens and applications
Think of it as a superhighway designed for speed and efficiency.

Network details#

PropertyMainnetTestnet (Devnet)
Network IDsolana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp
Block Explorerhttps://explorer.solana.comhttps://explorer.solana.com/?cluster=devnet
Block Time~400ms~400ms
Transaction Expiry~150 seconds (blockhash)~150 seconds (blockhash)

Supported assets#

USDC - USD Coin (stablecoin pegged to US Dollar)
Want to add other tokens? Kobaru is happy to support additional tokens upon request. Contact us at support@kobaru.io with your requirements.

USDC contract address#

Mainnet: EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v
Testnet: 4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU
Token Name: USD Coin
Token Symbol: USDC
Decimals: 6

Getting test tokens (faucet)#

For development and testing, get free USDC from the official Circle faucet:
Circle USDC Faucet:
Visit: https://faucet.circle.com/
Select "Solana Devnet" network
Choose "USDC" from the dropdown
Enter your wallet address
Complete the captcha
Claim free USDC

Popular wallets#

Phantom - https://phantom.app (Most popular)
Solflare - https://solflare.com

Tips for success#

1.
Keep it simple: USDC is the easiest to work with (price stable, widely available)
2.
Time limits: Transactions expire quickly (~2.5 minutes), so use them promptly
3.
Block explorer: You can see all your transactions at Kobaru's Console, but you can also see the inner workings at https://explorer.solana.com
4.
Start with devnet: Test everything on devnet before going live

Base#

What is Base?#

Base is a Layer 2 network built on Ethereum by Coinbase. Think of it as:
Ethereum's fast lane - Same security, faster and cheaper
EVM compatible - Works with Ethereum wallets and tools
Growing ecosystem - Connected to the broader crypto world
Base is perfect if your customers already use Ethereum wallets like MetaMask.

Network details#

PropertyMainnetTestnet (Sepolia)
Network IDeip155:8453eip155:84532
Block Explorerhttps://basescan.orghttps://sepolia.basescan.org
Block Time~2 seconds~2 seconds
Authorization WindowCustom (validAfter to validBefore)Custom (validAfter to validBefore)

Supported assets#

USDC - USD Coin (stablecoin pegged to US Dollar)
Want to add other tokens? Kobaru is happy to support additional tokens upon request. Contact us at support@kobaru.io with your requirements.

USDC contract address#

Mainnet: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
Testnet: 0x036CbD53842c5426634e7929541eC2318f3dCF7e
Token Name: USD Coin
Token Symbol: USDC
Decimals: 6
Want to add other tokens? Kobaru is happy to support additional tokens upon request. Contact us at support@kobaru.io with your requirements.

Getting test tokens (faucet)#

For development and testing on Base Sepolia, get free USDC from the official Circle faucet:
Circle USDC Faucet:
Visit: https://faucet.circle.com/
Select "Base Sepolia" network
Choose "USDC" from the dropdown
Enter your wallet address
Complete the captcha
Claim free USDC

Popular wallets#

MetaMask - https://metamask.io (Most common)
Coinbase Wallet - https://wallet.coinbase.com
Rainbow - https://rainbow.me

Tips for success#

1.
Time windows: Base payments use custom time windows (validAfter to validBefore), giving you more flexibility
2.
Authorization-based: Payments use EIP-712 signatures, which are more secure than raw transactions
3.
USDC: USDC is the standard token on Base

SKALE Base#

What is SKALE?#

SKALE is an app-specific blockchain network that offers unique advantages:
Low Gas Fees:
Transactions are very cheap
Predictable costs (no surprise gas spikes)
Perfect for high-volume APIs
Instant Finality:
No waiting for multiple confirmations
No chain forks or reorganizations
Payments settle in ~1 second
Privacy:
Encrypted transactions
Your customers' payment details stay private
Greater security for sensitive use cases
Native Bridge:
Seamless transfers between Base and SKALE
No third-party bridges needed
Built-in support for major tokens
Think of SKALE as a private, ultra-fast road for your payments.

Network details#

PropertyMainnetTestnet (Sepolia)
Network IDeip155:1187947933eip155:324705682
Block Explorerhttps://skale-base-explorer.skalenodes.com/https://base-sepolia-testnet-explorer.skalenodes.com/
Block Time~1 second~1 second
Authorization WindowCustom (validAfter to validBefore)Custom (validAfter to validBefore)

Supported assets#

USDC - USD Coin (stablecoin pegged to US Dollar)
Want to add other tokens? Kobaru is happy to support additional tokens upon request. Contact us at support@kobaru.io with your requirements.

USDC contract address#

Mainnet: 0x85889c8c714505E0c94b30fcfcF64fE3Ac8FCb20
Testnet: 0x2e08028E3C4c2356572E096d8EF835cD5C6030bD
Token Name: Bridged USDC (SKALE Bridge)
Token Symbol: USDC
Decimals: 6
Want to add other tokens? Kobaru is happy to support additional tokens upon request. Contact us at support@kobaru.io with your requirements.

Adding SKALE to your wallet#

MetaMask:
SKALE Base (Mainnet):
Network Name: SKALE Base
RPC URL: https://skale-base.skalenodes.com/v1/base
Chain ID: 1187947933
Currency Symbol: ETHC
Block Explorer: https://skale-base-explorer.skalenodes.com/
SKALE Base Sepolia (Testnet):
Network Name: SKALE Base Sepolia
RPC URL: https://base-sepolia-testnet.skalenodes.com/v1/jubilant-horrible-ancha
Chain ID: 324705682
Currency Symbol: ETHC
Block Explorer: https://base-sepolia-testnet-explorer.skalenodes.com/

Getting test tokens (faucet)#

For development and testing on SKALE Base Sepolia, follow these steps:
Step 1: Get ETH on Base Sepolia (for gas)
Visit: https://portal.cdp.coinbase.com/products/faucet
Select "Base Sepolia" network
Enter your wallet address
Claim free ETH (needed for bridging transaction fees)
Step 2: Get USDC on Base Sepolia
Visit: https://faucet.circle.com/
Select "Base Sepolia" network
Choose "USDC" from the dropdown
Enter your wallet address
Complete the captcha
Claim free USDC
Step 3: Bridge USDC from Base to SKALE
Visit: https://base-sepolia.skalenodes.com/bridge?from=mainnet&to=jubilant-horrible-ancha&token=usdc&type=erc20
Connect your wallet
Enter the amount of USDC to bridge
Approve and confirm the bridge transaction
USDC arrives on SKALE instantly

Getting tokens on mainnet#

To use SKALE Base on mainnet, you'll need ETH on Base for gas fees and USDC to bridge:
Note: You'll need a small amount of ETH on Base Mainnet to pay for the bridge transaction gas fees.
Bridge USDC from Base to SKALE Base:
Visit: https://base.skalenodes.com/bridge?from=mainnet&to=winged-bubbly-grumium&token=usdc&type=erc20
Connect your wallet
Enter the amount of USDC to bridge
Approve and confirm the bridge transaction
USDC arrives on SKALE instantly

Popular wallets#

MetaMask - https://metamask.io (Works with custom networks)
Coinbase Wallet - https://wallet.coinbase.com
Rainbow - https://rainbow.me
Any EVM-compatible wallet

Tips for success#

1.
Bridge first: You need to bridge tokens from Base to SKALE before making payments
2.
Zero gas: Remember, gas is pre-paid, so your customers don't need ETHC for fees
3.
Privacy advantage: SKALE transactions are encrypted by default
4.
Bridge portal: Use https://base.skalenodes.com for mainnet bridges

Choosing the right network#

When to choose Solana#

✅ Choose Solana if:
You want the fastest transaction times
Your customers use Phantom wallet
You're targeting Solana's ecosystem
You need sub-second confirmations
You are wiling to pay a premium on service fees
❌ Avoid Solana if:
Your customers use Ethereum wallets only
You need extensive smart contract features
You prefer the Ethereum ecosystem
You need extra low fees

When to choose Base#

✅ Choose Base if:
Your customers use Ethereum wallets (MetaMask, etc.)
You want EVM compatibility
You need a balance of speed and familiarity
You're building on Ethereum's ecosystem
❌ Avoid Base if:
You need absolute lowest fees
You require sub-second confirmations
You want maximum privacy

When to choose SKALE#

✅ Choose SKALE if:
Zero gas fees are critical
You need instant finality
Privacy is important for your use case
You want predictable costs
You have high transaction volumes
❌ Avoid SKALE if:
You need the largest ecosystem
You don't want to bridge tokens
Simplicity is your top priority

Common questions#

Do my customers need to hold gas tokens?#

No! The gateway pays all gas fees on all three networks. Your customers only need the payment amount (e.g., USDC).

Which network is fastest?#

SKALE (~1 second to finality) > Solana (~1-2 seconds to confirmation) > Base (~2 seconds)

Which network has the lowest fees?#

SKALE (gateway pays, extra low) > Solana (gateway pays, moderate) > Base (gateway pays, low)

Can I support multiple networks?#

Yes! You can enable all three networks and let your customers choose. This gives maximum flexibility.

Which network should I start with?#

For beginners: Start with Base. It's the most familiar and has great documentation.
For performance: Start with SKALE. Zero gas and instant confirmations.
For Solana ecosystem: Start with Solana.

Do I need different wallets for each network?#

Solana: Yes, needs a Solana wallet (Phantom, Solflare)
Base: No, uses Ethereum wallets (MetaMask)
SKALE: No, uses Ethereum wallets (MetaMask, just add custom network)

How do I test payments?#

1.
Choose a testnet (Solana Devnet, Base Sepolia, or SKALE Base Sepolia)
2.
Get test tokens from the faucets listed above
3.
Use your test API key
4.
Make test payments
5.
Verify on Kobaru's Console or the block explorer
Tip: You can use the Test Agent to simply test the end-to-end flow.

What happens if a transaction fails?#

All three networks have robust error handling:
Solana: Simulates before signing, fails fast if invalid
Base: Validates authorization before execution
SKALE: Same validation as Base
Your customers won't lose funds if a transaction fails.

Getting help#

Documentation#

Solana: https://docs.solana.com
Base: https://docs.base.org
SKALE: https://docs.skale.space
Tip: Check our API Paywall Cookbook with tangible, hands-on examples that go beyond basic documentation.

Support#

Kobaru Documentation: https://docs.kobaru.io
Email: support@kobaru.io
Status Page: https://status.kobaru.io

Important note for Viem users#

If you're using Viem (TypeScript interface for Ethereum) to integrate with Kobaru Gateway, please be aware of an important detail:

Token name fetching issue#

Viem's standard libraries may attempt to automatically fetch token metadata (name, symbol, decimals) by calling name() and symbol() functions on the token contract. While this works fine for most tokens on Base and Ethereum, it may fail for SKALE tokens due to contract-specific behaviors.

Recommended approach: Use the /supported endpoint#

Instead of hard-coding token information or relying on automatic fetching, retrieve token metadata from Kobaru's /supported endpoint. This ensures:
✅ Always correct - Token data comes directly from the facilitator
✅ Works on any network - No special handling needed for SKALE, Base, or Solana
✅ Future-proof - New tokens will work automatically

Example: Getting token metadata#

Complete example#

For a complete working example, see the Kobaru API Paywall Cookbook:
Repository: https://github.com/fabriciogava/api-paywall-cookbook/tree/main/examples/nodejs/deep-thought-api
This example demonstrates:
Fetching token metadata from /supported
Creating EIP-712 typed data signatures
Submitting payments to the gateway
Handling errors and retries

Next steps#

1.
Choose a network based on your needs
2.
Set up a test wallet on that network
3.
Get test tokens from the faucet
4.
Test payments using your test API key
5.
Go live when ready!
Ready to integrate? Check out our API documentation or contact support for help getting started.
Modified at 2026-01-20 17:29:46
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