ERC721 on StarkNet




Welcome! This is an automated workshop that will explain how to deploy an ERC721 token on StarkNet and customize it to perform specific functions.
It is aimed at developers that:

  • Understand Cairo syntax
  • Understand the ERC721 token standard

This workshop is the first in a series that will cover broad smart contract concepts (writing and deploying ERC20/ERC721, bridging assets, L1 <-> L2 messaging…).
Interested in helping writing those? Reach out!


Don’t expect any kind of benefit from using this, other than learning a bunch of cool stuff about StarkNet, the first general purpose validity rollup on the Ethereum Mainnnet.

StarkNet is still in Alpha. This means that development is ongoing, and the paint is not dry everywhere. Things will get better, and in the meanwhile, we make things work with a bit of duct tape here and there!

Providing feedback

Once you are done working on this tutorial, your feedback would be greatly appreciated!
Please fill this form to let us know what we can do to make it better.

And if you struggle to move forward, do let us know! This workshop is meant to be as accessible as possible; we want to know if it’s not the case.

Do you have a question? Join our Discord server, register and join channel #tutorials-support

How to work on this TD


The TD has three components:

  • An ERC20 token, ticker ERC721-101, that is used to keep track of points
  • An evaluator contract, that is able to mint and distribute ERC721-101 points
  • A second ERC20 token, ticker DTK, that is used to make fake payments

Your objective is to gather as many ERC721-101 points as possible. Please note :

  • The ‘transfer’ function of ERC721-101 has been disabled to encourage you to finish the TD with only one address
  • You can answer the various questions of this workshop with different ERC721 contracts. However, an evaluated address has only one evaluated ERC721 contract at a time. To change the evaluated ERC721 contract associated with your address, call submit_exercise() within the evaluator with that specific address.
  • In order to receive points, you will have to do execute code in Evaluator.cairo such that the function distribute_points(sender_address, 2) is triggered, and distributes n points.
  • This repo contains an interface IExerciceSolution.cairo. Your ERC721 contract will have to conform to this interface in order to validate the exercise; that is, your contract needs to implement all the functions described in IExerciceSolution.cairo.
  • A high level description of what is expected for each exercise is in this readme. A low level description of what is expected can be inferred by reading the code in Evaluator.cairo.
  • The Evaluator contract sometimes needs to make payments to buy your tokens. Make sure he has enough dummy tokens to do so! If not, you should get dummy tokens from the dummy tokens contract and send them to the evaluator

Checking your progress

Counting your points

Your points will get credited in Argent X; though this may take some time. If you want to monitor your points count in real time, you can also see your balance in voyager!

  • Go to the ERC20 counter in voyager, in the “read contract” tab
  • Enter your address in decimal in the “balanceOf” function

Transaction status

You sent a transaction, and it is shown as “undetected” in voyager? This can mean two things:

  • Your transaction is pending, and will be included in a block shortly. It will then be visible in voyager.
  • Your transaction was invalid, and will NOT be included in a block (there is no such thing as a failed transaction in StarkNet).

    You can (and should) check the status of your transaction with the following URL , where you can append your transaction hash.

Getting to work

  • Clone the repo on your machine
  • Set up the environment following these instructions
  • Install Nile.
  • Test that you are able to compile the project
nile compile

Points list

Today we are creating an animal registry! Animals are bred by breeders. They can be born, die, reproduce, be sold. You will implement these features little by little.

ERC721 basics

  • Create an ERC721 token contract. You can use this implementation as a base
  • Deploy it to the testnet
  • Give token #1 to Evaluator contract
  • Call submit_exercise() in the Evaluator to configure the contract you want evaluated (2 pts)
  • Call ex1_test_erc721() in the evaluator to receive your points (2 pts)
  • Call ex2a_get_animal_rank() to get assigned a random creature to create.
  • Read the expected characteristics of your animal from the Evaluator
  • Create the tools necessary to record animals characteristics in your contract
  • Mint the desired animal and give it to the evaluator
  • Call ex2b_test_declare_animal() to receive points (2 pts)

Minting and burning NFTs

  • Create a function to allow breeders to declare new animals
  • Call ex3_declare_new_animal() to get points (2 pts)
  • Create a function to allow breeders to declare dead animals
  • Call ex4_declare_dead_animal() to get points (2 pts)

Adding permissions and payments

  • Use dummy token faucet to get dummy tokens
  • Use ex5a_i_have_dtk() to show you managed to use the faucet (2 pts)
  • Create a function to allow breeder registration.
  • This function should charge the registrant for a fee, paid in dummy tokens
  • Add permissions. Only allow listed breeders should be able to create animals
  • Call ex5b_register_breeder() to prove your function works. If needed, send dummy tokens first to the evaluator (2pts)

Minting NFTs with Metadata

Not automated yet, but you can still have fun

  • Mint an NFT with metadata on contract 0x0447e9377de46a1b6d46ca00311f51c9613831a803dc8085e5b8e0f69db19a6d (through voyager, function mint_with_metadata)
  • You can use these assets
  • Check it on Oasis
  • Create a new ERC721 contract that supports metadata. You can use this contract as a base
  • Each token should have an associated IPFS hash. So you’ll need to modify the functions reading/writing/storing the URIs
  • The base token URI is the chosen IPFS gateway
  • You can upload your NFTs directly on this website
  • Your tokens should be visible on Oasis once minted!

Exercises & Contract addresses

Contract code Contract on voyager
Points counter ERC20 0x0272abeb08a98ce2024b96dc522fdcf71e91bd333b228ad62ca664920881bc52
Evaluator 0x06fc9fab4bf90473b2d3b847855e39a696c11fd8455bc59e344183a40c3a28df
Dummy token 0x06a60bee530501ec2d6368d751cea17122ecbdf9cb8f1724a50f22cc8f73d7f5


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