Sublimate Finance

Sublimate is a DeFi smart contract app that lets artists, open-source developers, and content creators accept continuous financial support from anyone in the form of streamable tokens.

For supporters: • Reward your favorite artists, builders, and content creators on a continual basis, at your own pace. • Mint streamable tokens (strETH, strDAI, etc.) by depositing ETH, DAI or any ERC-20 token. • Start a "streamable subscription" to a recipient by choosing a token, a duration, and a rate or maximum amount. Funds will be streamed out of your balance and into the recipient's every time a block is added to the blockchain. You can cancel a subscription at any time. • You pay gas fees only when starting/canceling subscriptions, and converting between streamable and non-streamable tokens. There are no recurring fees during the subscription itself.

For creators: • Connect your wallet address to build a personalized "creator page" ready to receive streamable tokens. You'll get a custom sublimate.finance link to share to your fans and followers (optionally personalizable by connecting an ENS name, e.g. sublimate.finance/creator/vitalik.eth). • Track your balance, number of supporters, and other analytics using our built in dashboard powered by The Graph. • Use our embeddable subscribe widget so anyone can support you from your newsletter, blog or website. • Pay it forward – showcase other creators you're supporting!

Smart contract protocol: Streamable Tokens

• The StreamableERC20 contract is a modified ERC-20 implementation overriding the balanceOf() and transfer() methods.

• A subscription is defined as a rate expressed in tokens per block and a maximum amount of tokens to send. The incoming and outgoing subscriptions for each address are stored as a struct within a double mapping indexed by the "from" and "to" addresses.

• The balance of streamable tokens can be dynamically computed at any time, using the following formula: balance = lastUpdatedBalance + (incomingRate - outgoingRate) * (block - lastUpdatedBlock). Subscriptions can be canceled at any time by the sender.

• We implemented wrapping contracts for ETH and existing ERC20 tokens. This means creating a streamable version of any currency (for instance, DAI) is as easy as deploying StreamableWrappedERC20 with the corresponding underlying token address in the constructor.

• Our current implementation is quite limited; all subscriptions must be funded up-front and last a finite duration to prevent any malfunction of the contract's logic. For future implementations, we're planning to support unfunded and endless subscriptions (e.g. subscribe for 1 year without holding the full amount up front, or even forever), as well as multiple subscriptions to the same address.

• We're working on updating the protocol to allow streamable versions of Aave's interest bearing tokens, so creators and subscribers can earn extra interest while supporting each other.

• We're exploring the use of a new Chainlink feed that will track the average block time of the past day/month/year, so that instead of taking a rate of tokens per block, our smart contract can take a time interval as input and accurately estimate how many blocks a subscription should last.

Smart contracts: StreamableWrappedETH and StreamableDAI

• We used Solidity and the Hardhat development environment to develop the smart contracts, and the Chai library for tests.

• StreamableWrappedETH and StreamableDAI are deployed to the Kovan testnet

• Our contracts are ready to deploy to Matic so our users can support their favorite creators without the friction of exorbitant gas fees.

The Graph: Sublimate subgraph

• Our subgraph calculates block-by-block analytics for users of streamable tokens, including subscriber counts, account balances and net incoming and outgoing rates across all subscriptions.

• Entities include User, StreamableToken, and StreamableSubscription.

• We used event handlers to index the state of all subscriptions, and a block handler to index the balance/amount transferred at every block for all accounts and subscriptions.

• The subgraph is deployed to The Graph's hosted service, indexing on Kovan: https://thegraph.com/explorer/subgraph/sublimate-finance/sublimate

• We started integrating Chainlink's price oracles in the subgraph indexer to accurately calculate the total fiat value of a subscription, since each bit of token streamed within a subscription can have a different price.

Front-end: Svelte Single-Page Application

• We used TypeScript and the Svelte/Sapper web framework to build our dapp as a dynamic single page application. It can be installed as a progressive web app or even deployed to IPFS for censorship resistance.

• The front-end uses ethers.js to make smart contract calls and urql to make GraphQL requests to our subgraph on The Graph.

Back-end: Profile Editing

• Our back-end lets creators associate custom profile information with their Ethereum address to display on their http://sublimate.finance creator page, including an avatar image, cover image, short description and social network links.

• We opted for an off-chain solution using a cloud database and lambda function, deployed to AWS. Editing your profile is as simple as signing the new profile contents with your address through your wallet and making a POST request to the lambda function. (On-chain profile editing would require a transaction at each modification since it changes the state of the EVM.)

Sponsor technologies integrated: ENS, The Graph, AAVE, Matic, Chainlink