Coinbase Web Transaction Tax Report Helper

WHAT IT DOES

This userscript helps Coinbase users prepare cryptocurrency tax reports by extracting and analyzing their transaction history. It scans the Coinbase web app transaction history page and extracts key data—date, transaction type (buy, sell, send, receive, convert), asset, quantity, price, and fiat value. The script then formats the data as CSV or JSON for use in tax preparation software or spreadsheets. It can calculate realized gains and losses using FIFO (First In, First Out) or LIFO (Last In, First Out) accounting methods, aggregate totals by asset, and generate a comprehensive summary report. It can also filter transactions by tax year and includes options to include or exclude send/receive transactions and transfer fees.

WHERE IT RUNS

The script works specifically on the Coinbase web app transaction history page (coinbase.com). It runs entirely within your browser, reading only the visible content of the current page. It does not track your browsing history, access other tabs, or send any data externally. No external API calls are made—all extraction, calculation, and formatting is performed locally.

HOW TO USE

After installation, open the panel by clicking the tool's icon in the BotGentz sidebar. First, navigate to your Coinbase transaction history page. Choose your export format—CSV (compatible with Excel, Google Sheets, and most tax software) or JSON (for developers). Select your preferred tax accounting method—FIFO (sell oldest first) or LIFO (sell newest first). Toggle "Calculate gains/losses" to include capital gain calculations, "Include Send/Receive transactions" to add non-trading transactions, and "Auto-download on scan" to automatically download when scanning. Click "Scan and export" to extract the data, calculate gains, and download the file. The panel will display a summary of the extracted data.

THE TECHNICAL MECHANISM

This script uses DOM traversal and pattern matching to extract transaction data from the Coinbase web app. It scans the page for transaction elements using common class names like [class*="transaction"], [role="row"], and data-testid patterns. For each transaction, it extracts text and applies regex patterns to identify dates (multiple formats), transaction types (Buy, Sell, Send, Receive, Convert), assets (40+ cryptocurrency tickers), quantities, prices, and totals. The script includes an auto-scroll function that programmatically scrolls the transaction history container to trigger pagination loading, waiting for new content before extracting. For gain calculations, the script groups transactions by asset, sorts them chronologically, then applies FIFO or LIFO logic—matching sell orders to the earliest (FIFO) or latest (LIFO) buys. It calculates proceeds (sell quantity × sell price), cost basis (matched buy quantity × buy price), and realized gain (proceeds minus cost basis). All transactions and gains are exported in the selected format with full summary statistics.

THE PANEL

The panel is draggable anywhere on the screen and remembers its position between sessions. It can be collapsed to a small floating bubble to minimize distraction, and expanded again with a single click. The panel's width can be adjusted, and pressing the Escape key closes it instantly. All settings—export format, tax method, include gains, include send/receive, and auto-download—are persisted locally using GM_setValue, so your preferences remain intact across page reloads and browser restarts.

PLEASE NOTE

This userscript requires the free BotGentz extension to function. The script is designed for the Coinbase web app; it will not work on the mobile app or other websites. The transaction extraction relies on the current structure of the Coinbase web app—if Coinbase updates their UI, the script may need to be updated. The gain calculations are estimates based on the transaction data extracted; they should be verified against your official Coinbase tax statements before filing. The script does not access your Coinbase account credentials or API; it only reads what is visible on the page. This tool is for informational purposes and does not constitute tax advice. No data from your browsing is stored or transmitted anywhere—all processing occurs entirely in your browser.