gistfile1.txt

Product: a crypto portfolio value tracker

During this conversation, we’ll talk about building a cryptocurrency portfolio tracker. Users can track the value of their portfolio across various cryptocurrencies.

Features

- Track token (cryptocurrency) prices
- Track the value of your own token holdings
- Add historical transactions (i.e. when the user bought or sold a token)
    - Fields:
        - Token (i.e. Bitcoin)
        - Date / Time
        - Price (i.e. $50,000 USD per BTC)
        - Amount (i.e. 0.4 BTC)
- Show portfolio total balance
- Show historical portfolio performance
- Bonus features
    - Work with multiple base currencies (not just USD)
    - Work with multiple portfolios

Product constraints:


- You can get price data from a pre-existing API with no rate limits or authentication.
- All data is stored on the client. No backend database is allowed for storing user data. 
- Don't worry about authentication or syncing data across devices.

Wireframes


![Home page - portfolio view](https://paper-attachments.dropbox.com/s_EAA04FC639CB25FBBA330F95E8FDDBC1210C440493C2212A6B4E44EB577243DD_1615597817832_image.png)

![1. Landing Page](https://paper-attachments.dropbox.com/s_EAA04FC639CB25FBBA330F95E8FDDBC1210C440493C2212A6B4E44EB577243DD_1615597674180_image.png)
![2. Track a token](https://paper-attachments.dropbox.com/s_EAA04FC639CB25FBBA330F95E8FDDBC1210C440493C2212A6B4E44EB577243DD_1615597694442_image.png)

![Viewing a specific token](https://paper-attachments.dropbox.com/s_EAA04FC639CB25FBBA330F95E8FDDBC1210C440493C2212A6B4E44EB577243DD_1615597933758_image.png)
![Add a portfolio transaction](https://paper-attachments.dropbox.com/s_EAA04FC639CB25FBBA330F95E8FDDBC1210C440493C2212A6B4E44EB577243DD_1615597981018_image.png)


User flows


- Track a token (not in their portfolio)
- See list of tracked tokens, no "portfolio" history
- View a token
    - See price history of token
- Add a transaction
- View portfolio history, incorporating past balances and prices

Example of how the app works:

- I bought 1 BTC and 50,000 STX a week ago, each purchase worth $50,000
    - My portfolio was worth $100,000
- Today, BTC has gone down by 5%, and STX has gone up by 10%.
    - My Bitcoin is now worth $47,500
    - My Stacks are worth $55,000
    - My portfolio is now worth $102,500
    - My portfolio is up 2.5%

API

Assume that an API for fetching historical price data is fully available.

Example APIs:

Get historical prices for a token

- `https://myapi.com/tokens/STXUSD/historical`
- Prices are reverse-chronological
- Assume you can use query parameters to change offset and interval
    - `?before=1615581722112` - prices before timestamp
    - `?interval=1d` - interval between each price tick
- Example response:
    {
      results: [
        {
          price: 1.0503,
          timestamp: 1615581722112
        },
        {
          price: 1.04,
          timestamp: 1615581722112
        }
      ]
    }

Websocket for real-time price updates

- Example WebSocket message:
    {
      ticker: 'STXUSD',
      price: 1.1725,
    }