Token distributors in Scilla

This article explains how the Merkle tree-based token distributors work on Zilliqa using Scilla. The implementations of this contract can be found in Zwap weekly distribution, REDC LMR distributions, and others as well.

Most of the platforms use merkle tree-based distributors because transferring tokens to individual accounts would cost too much gas. Also, updating the contract addresses and their amount in the distributor contract itself. This is where merkle tree-based distributors come in. They enable platforms to distribute tokens through distributors in a more simplified and gas-efficient way. Merkle roots are used to verify whether the address claiming token from the contracts is valid or not.


From all the addresses and the amount to which the tokens are to be distributed, merkle root is calculated. An admin/oracle/backend updates the distributor contract with the merkle root.

Zwap distributor contract’s transition for setting merkle root

After the merkle root is set, the address which is supposed to get the tokens from the distributor, generates a merkle hash proof from the backend of the distributors and supply the epoch number(the period of token distribution), amount, and proof of the leaf node. The distributor contract verifies the proof and distributes the token to the users who are claiming tokens.

Zwap distributor contract’s transition for claiming token

The data provided by the users to claim tokens with the merkle proof consists of epoch number, address, amount, and an array of proof hashes as below.

Data inputs for claim transition of the distributor contract

Code References

Zwap distributor contract

Zwap distributor backend

Script for setting merkle root and claiming tokens

More detailed description about merkle trees and the code can be found in the next article of Merkle tree and proofs for distributor.




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Bibek Koirala

Bibek Koirala

A blockchain dev | Zilliqa Developer Ambassador | RedChillies Labs, Inc. | Pastel Soft | JS Security Technologies | AART

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