Toucan SDK

The Toucan SDK allows developers to build using Toucan's infrastructure tools on Celo and Polygon. It provides a set of functions that allow developers to interact with Toucan Protocol's smart contracts and subgraphs. This includes redeeming of pool tokens and retirements of carbon credits, as well as querying data on projects and retirements.

A Typescript SDK for Toucan Protocol. Wraps around Ethers.js. Works in the web browser and Node.js.

For the full documentation, check our docs.

⚠️ This SDK is heavily under development. USE AT YOUR OWN RISK. ⚠️

Install

npm i toucan-sdk

or

yarn add toucan-sdk

Quickstart

Instantiate the ToucanClient and set a signer & provider to interact with our infrastructure.

We recommend using to use ethers.js ^5.6.4 for the signer and provider. When you are considering using wagmi, only versions under 1.0 will work as this library has not yet been upgraded to viem.

ethers.js

import ToucanClient from "toucan-sdk";
import { ethers } from "ethers";

// ethers signer and provider
const provider = new ethers.providers.JsonRpcProvider(
  "https://rpc.ankr.com/polygon"
);

// make sure to set your private key in your .env file
const signer = new ethers.Wallet(process.env.PRIVATE_KEY, provider);

// set signer & provider
const toucan = new ToucanClient("alfajores", provider, signer);

wagmi

import { ToucanClient } from "toucan-sdk";
import { useProvider, useSigner } from "wagmi";

// get signer & provider
const { data: signer } = useSigner();
const provider = useProvider();

// set signer & provider
const toucan = new ToucanClient("alfajores", provider, signer);

You could also set the signer/provider later if you prefer that. They are optional. But you will need to set them if you want to interact with contracts. The provider is read-only, while the signer allows both writing to and reading from the blockchain.

import ToucanClient from "toucan-sdk";

const toucan = new ToucanClient("alfajores");
toucan.setProvider(provider);
toucan.setSigner(signer);

If you don't have a signer nor a provider set, you can only interact with the subgraph.

Fetch pool prices from a Dex

You can find pools for Toucan pool tokens on Celo Network at Uniswap and for Polygon Network on SushiSwap.

Something that may come in handy in your applications is fetching the USD price of our pool tokens.

nctPrice = await toucan.fetchTokenPriceOnDex("NCT");

The object returned by the above method will look like this:

{
  "price": 0.6729727912290213,
  "url": "https://info.ubeswap.org/token/0xfb60a08855389F3c0A66b29aB9eFa911ed5cbCB5",
  "liquidityUSD": 6094809.639784346,
  "volumeUSD": 2343496099.964215
}

Interact with Toucan's Contracts?

You can always access any method or property of the BCT, NCT and TCO2 contracts by first getting and storing them in a variable, like this:

toucan.setSigner(signer);

const nct = await toucan.getPoolContract("NCT");
const tco2 = await toucan.getTCO2Contract(tco2Address);
const registry = await toucan.getRegistryContract();
const remainingTCO2 = await nct.tokenBalances(tco2Address);

This is useful if you need to interact with a method of our contracts that hasn't been implemented in the SDK yet.

It's important to note that, if you want to use write methods you need to have a signer set in your ToucanClient!

Example to retire Carbon Credits

To retire Carbon Credits on mainnet, you will have to get Carbon Pool Tokens from a DEX like Uniswap, which you need to redeem for TCO2s. You can then retire these and get a certificate for that. If you already own NCTs, you can follow this example. In case you don't and are developing on testnet, you can also just get some at the Toucan Faucet. You can find more ways to retire in our documentation.

Redeem your Pool Tokens and get an array of redeemed TCO2s

const tco2Addresses = await toucan.redeemAuto("NCT", parseEther("1"));

Retire the Carbon Credits

await toucan.retire(parseEther("1"), tco2Addresses[0].address);

Subgraph queries

Now, the above example of selective retirement is only useful in specific cases.

What if you only have the name or symbol of the project?

That's where subgraph queries come in handy. (and we have plenty of those 😉) - But feel free to also create your own.

Make sure all addresses are input in lowercase letters, as the queries are case sensitive.

Fetching a TCO2 by its symbol

const tco2 = await toucan.fetchTCO2TokenByFullSymbol("TCO2-VCS-1718-2013");

The result will look like this:

{
  "id": "0x0044c5a5a6f626b673224a3c0d71e851ad3d5153",
  "name": "Toucan Protocol: TCO2-VCS-1718-2013",
  "symbol": "TCO2-VCS-1718-2013",
  "address": "0x0044c5a5a6f626b673224a3c0d71e851ad3d5153",
  "projectVintage": {
    "name": "2013",
    "project": {
      "projectId": "VCS-1718"
    }
  }
}

Now you have quite some info on the project, including its address.

All queries:

Toucan SDK offers a lot of pre-defined queries. Try them out!

import { ToucanClient } from "toucan-sdk";

// here we don't need to set the signer or provider
const toucan = new ToucanClient("alfajores");

// Fetch the batches of a user.
await toucan.fetchUserBatches(address: string, first?: number, skip?: number);

// Fetch TCO2 token by its address to get details like name, symbol, address and projectVintage.
await toucan.fetchTCO2TokenById(address: string);

// Fetch TCO2Token with the symbol to get details like name, symbol, address and projectVintage. A symbol would look like this: `TCO2-VCS-<projectId>-YYYY`. Make sure to input the full symbol.
await toucan.fetchTCO2TokenByFullSymbol(symbol: string);

// Fetch all TCO2s details like name, symbol, address and projectVintage.
await toucan.fetchAllTCO2Tokens(first?: number, skip?: number);

// Fetch all user retirements to get information like creationTX, amount, token details and certificate details.
await toucan.fetchUserRetirements(address: string, first?: number, skip?: number);

// Fetch all redeems of a given pool to get information like amount, creator and token details. Only accepts the Pooltypes "NCT" or "BCT".
await toucan.fetchRedeems(poolSymbol: Pooltypes, first?: number, skip?: number);

// Fetch all redeems of a user by pool and get information like amount and token details.
await toucan.fetchUserRedeems(address: string, poolSymbol: Pooltypes, first?: number, skip?: number);

// Fetch TCO2 tokens that are part of the given pool and get information on name, amount, methodology and more.
await toucan.fetchPoolContents(poolSymbol: Pooltypes, first?: number, skip?: number);

// Fetch a project by it's id (e.g., Verra Project ID) to get more info on region and the standard.
await toucan.fetchProjectById(id: string);

// Fetch all aggregations (including for example, tco2TotalRetired or totalCarbonBridged).
await toucan.fetchAggregations();

Custom queries

Now that you have an overview of our pre-build queries, let's have a look at the fetchCustomQuery method.

This allows you to fetch with your own queries and can be very powerful if you know graphQL. You can also check out a lot of example queries in our subgraph playgrounds.

• Getting all infos on a carbon project (region stands for the country)

import { gql } from "@urql/core";
import { ToucanClient } from "toucan-sdk";

const toucan = new ToucanClient("alfajores");

const query = gql`
  query ($id: String) {
    project(id: $id) {
      projectId
      region
      standard
      methodology
      vintages {
        id
      }
    }
  }
`;

const result = await toucan.fetchCustomQuery(query, { id: "1" });

Auto Offset using the OffsetHelper

Auto Offset CO2

Using the OffsetHelper methods is the easiest way to offset CO2 right now as it handles the whole process for you.

(Uses Ubeswap/SushiSwap to acquire BCT/NCT, redeems it for TCO2s and retires them)

This is how you do that when you want to use ETH (or the network's native currency) in your balance.

In this example, you'd be offsetting 1 TON of CO2 with carbon projects from the NCT pool.

const offsetReceipt = await toucan.autoOffsetExactOutETH(
  "NCT",
  parseEther("1.0")
);

Don't want to spend your ETH to offset?

You can use different tokens to do it. Currently it works with cUSD, USDC, WMATIC and WETH.

const weth = new ethers.Contract(wethAddress, wethAbi, signer);

const offsetReceipt = await toucan.autoOffsetExactInToken(
  "NCT",
  parseEther("1.0"),
  weth
);

Offset with your own BCT/NCT

If you already have BCT/NCT, you can use autoOffsetPoolToken() like this:

const offsetReceipt = await toucan.autoOffsetPoolToken(
  "NCT",
  parseEther("1.0")
);

Selectively Offset CO2

You may want to selectively offset certain carbon projects. You can do that too.

Assuming you already have some NCT, this example gets an array of all TCO2s in the NCT pool ascending by rank/quality.

Then redeems and retires 3 TONS of the highest ranked TCO2 it can find.

const scoredTCO2s = await toucan.getScoredTCO2s("NCT");
const len = scoredTCO2s.length;

const redeemReceipt = await toucan.redeemMany(
  "NCT",
  [scoredTCO2s[len - 1]],
  [parseEther("3.0")]
);

const retirementReceipt = await toucan.retire(
  parseEther("3.0"),
  tco2s[len - 1].address
);

Of course, you could have avoided using the getScoredTCO2s method if you already had the address of the TCO2s you wanted to offset.

But I want the Retirement NFT

If you do, that's also quite easy to pull off. You just replace the usage of the retire() method in the example above with this:

const retirementReceipt = await toucan.retireAndMintCertificate(
  "Alice",
  bobsAddress,
  "Bob",
  "Just helping the planet",
  parseEther("3.0"),
  tco2s[len - 1].address
);

"Alice" represents the entity that is doing the retirement/offset. The second name represents the party that 'benefits' from it, in this case "Bob". We will also add Bob's address so now the relation of the certificate is set to that address instead of the retiring party.

This useful in case you happen to be an entity that retires on behalf of someone else.