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Documentation Index

Fetch the complete documentation index at: https://mintlify.com/ckb-devrel/ccc/llms.txt

Use this file to discover all available pages before exploring further.

CCC uses a declarative transaction model: you describe what you want the transaction to do, then call helpers to fill in the rest automatically — collecting inputs, calculating fees, and broadcasting.

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Core concepts

On CKB, every output must declare its capacity in shannon (1 CKB = 10⁸ shannon). Use ccc.fixedPointFrom(amount) to convert a human-readable CKB amount to the internal representation: 
ccc.fixedPointFrom(100)    // 100 CKB → 10_000_000_000n shannon
ccc.fixedPointFrom("0.01") // 0.01 CKB → 1_000_000n shannon

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Transfer CKB

The following example (from packages/examples/src/transfer.ts) sends exactly 100 CKB to a receiver address:
1

Describe the outputs

Create a transaction skeleton with just the outputs you want. CCC will figure out which inputs are needed.
import { ccc } from "@ckb-ccc/ccc";

const receiver = await signer.getRecommendedAddress();
const { script: lock } = await ccc.Address.fromString(receiver, signer.client);

const tx = ccc.Transaction.from({
  outputs: [{ capacity: ccc.fixedPointFrom(100), lock }],
});
2

Fill inputs by capacity

completeInputsByCapacity queries live cells owned by the signer and adds them as inputs until the total capacity covers all outputs.
await tx.completeInputsByCapacity(signer);
3

Pay the fee

completeFeeBy adds a change output back to the signer and adjusts its capacity to cover the network fee. The fee rate is calculated automatically based on current network conditions.
await tx.completeFeeBy(signer);
4

Sign and broadcast

const txHash = await signer.sendTransaction(tx);
console.log("Transaction hash:", txHash);

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Transfer all CKB

To sweep all CKB from an account — for example when emptying a wallet — use completeInputsAll combined with completeFeeChangeToOutput. This example is from packages/examples/src/transferAll.ts: 
import { ccc } from "@ckb-ccc/ccc";

const receiver = await signer.getRecommendedAddress();
const { script: lock } = await ccc.Address.fromString(receiver, signer.client);

// No capacity set — we'll fill it after collecting all inputs
const tx = ccc.Transaction.from({
  outputs: [{ lock }],
});

// Collect every cell owned by the signer as inputs
await tx.completeInputsAll(signer);

// Deduct fee from output 0 and send all remaining CKB there
await tx.completeFeeChangeToOutput(signer, 0);

const txHash = await signer.sendTransaction(tx);
completeFeeChangeToOutput(signer, 0) adjusts the capacity of the output at index 0 downward to pay the fee. Make sure that output exists before calling this method.

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Fee calculation

You never need to set fee rates manually. CCC fetches the current median fee rate from the node and uses it automatically when you call completeFeeBy or completeFeeChangeToOutput. If you need fine-grained control you can pass an explicit fee rate (in shannon per kilobyte) as the second argument: 
// Pay fee at a fixed rate of 1000 shannon/kB
await tx.completeFeeBy(signer, 1000);

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API reference

MethodDescription
ccc.Transaction.from(skeleton)Create a transaction from a partial description
ccc.fixedPointFrom(amount)Convert CKB amount to shannon (bigint)
tx.completeInputsByCapacity(signer)Add inputs until capacity is sufficient
tx.completeInputsAll(signer)Collect all cells owned by the signer
tx.completeFeeBy(signer, feeRate?)Add change output and pay fee
tx.completeFeeChangeToOutput(signer, index, feeRate?)Deduct fee from a specific output
signer.sendTransaction(tx)Sign and broadcast; returns tx hash
Try these examples interactively in the CCC playground at live.ckbccc.com.

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