Stock Prices API Skill
This skill helps you work with the Stock Prices API to fetch real-time market data and stock quotes.
API Endpoint
Base URL: https://stock-prices.on99.app
Primary Endpoint: /quotes?symbols={SYMBOLS}
Quick Start
Fetch stock quotes for one or more symbols (responses are in TOON format):
curl "https://stock-prices.on99.app/quotes?symbols=NVDA"
curl "https://stock-prices.on99.app/quotes?symbols=AAPL,GOOGL,MSFT"
Install the TOON decoder for parsing: pnpm add @toon-format/toon
Response Format
The API returns TOON (Token-Oriented Object Notation) format—a compact, human-readable encoding that uses ~40% fewer tokens than JSON. This makes it ideal for LLM prompts and streaming.
TOON Response Example
quotes[1]{symbol,currentPrice,change,percentChange,highPrice,lowPrice,openPrice,previousClosePrice,preMarketPrice,preMarketChange,preMarketTime,preMarketChangePercent,...}:
NVDA,188.54,-1.5,-0.789308,192.48,188.12,191.405,190.04,191.8799,3.3399048,2026-02-11T13:49:16.000Z,1.771457,...
Decoding TOON Responses
Use @toon-format/toon to parse responses back to JavaScript/JSON:
import { decode } from "@toon-format/toon";
const response = await fetch("https://stock-prices.on99.app/quotes?symbols=NVDA");
const toonText = await response.text();
const data = decode(toonText);
// data.quotes is an array of quote objects
const quote = data.quotes[0];
console.log(`${quote.symbol}: $${quote.currentPrice}`);
The decoded structure matches JSON—same objects, arrays, and primitives.
Available Data Fields
| Field | Type | Description |
|---|---|---|
symbol | string | Stock ticker symbol |
currentPrice | number | Current trading price |
change | number | Price change from previous close |
percentChange | number | Percentage change from previous close |
highPrice | number | Day's high price |
lowPrice | number | Day's low price |
openPrice | number | Opening price |
previousClosePrice | number | Previous day's closing price |
preMarketPrice | number | Pre-market trading price |
preMarketChange | number | Pre-market price change |
preMarketTime | string (ISO 8601) | Pre-market data timestamp |
preMarketChangePercent | number | Pre-market percentage change |
Usage Guidelines
Multiple Symbols
Query multiple stocks by separating symbols with commas (max 50):
curl "https://stock-prices.on99.app/quotes?symbols=AAPL,GOOGL,MSFT,TSLA,AMZN"
Error Handling
Always check for valid responses. Decode TOON before accessing data:
import { decode } from "@toon-format/toon";
const response = await fetch("https://stock-prices.on99.app/quotes?symbols=NVDA");
const data = decode(await response.text());
if (data.quotes && data.quotes.length > 0) {
const quote = data.quotes[0];
console.log(`${quote.symbol}: $${quote.currentPrice}`);
}
Price Analysis
Calculate common metrics:
// Determine if stock is up or down
const isUp = quote.change > 0;
const direction = isUp ? "📈" : "📉";
// Calculate day's range percentage
const rangePct = ((quote.highPrice - quote.lowPrice) / quote.lowPrice) * 100;
// Compare current to open
const vsOpen = quote.currentPrice - quote.openPrice;
Common Use Cases
1. Price Monitoring
import { decode } from "@toon-format/toon";
async function checkPrice(symbol: string) {
const res = await fetch(`https://stock-prices.on99.app/quotes?symbols=${symbol}`);
const data = decode(await res.text());
const quote = data.quotes[0];
return {
price: quote.currentPrice,
change: quote.change,
changePercent: quote.percentChange,
};
}
2. Portfolio Tracking
import { decode } from "@toon-format/toon";
async function getPortfolio(symbols: string[]) {
const symbolString = symbols.join(",");
const res = await fetch(`https://stock-prices.on99.app/quotes?symbols=${symbolString}`);
const data = decode(await res.text());
return data.quotes.map(q => ({
symbol: q.symbol,
value: q.currentPrice,
dailyChange: q.percentChange,
}));
}
3. Market Summary
import { decode } from "@toon-format/toon";
async function marketSummary(symbols: string[]) {
const res = await fetch(`https://stock-prices.on99.app/quotes?symbols=${symbols.join(",")}`);
const data = decode(await res.text());
const gainers = data.quotes.filter(q => q.change > 0);
const losers = data.quotes.filter(q => q.change < 0);
return {
totalStocks: data.quotes.length,
gainers: gainers.length,
losers: losers.length,
avgChange: data.quotes.reduce((sum, q) => sum + q.percentChange, 0) / data.quotes.length,
};
}
Popular Stock Symbols
Tech Giants (FAANG+)
AAPL- AppleGOOGL- Alphabet (Google)META- Meta (Facebook)AMZN- AmazonNFLX- NetflixMSFT- Microsoft
High-Profile Stocks
NVDA- NVIDIATSLA- TeslaAMD- Advanced Micro DevicesINTC- IntelORCL- Oracle
Indices
^GSPC- S&P 500^DJI- Dow Jones^IXIC- NASDAQ
Notes
- Response format: API returns TOON, not JSON. Use
decode()from@toon-format/toonto parse. - All prices are in USD
- Data updates in real-time during market hours
- Pre-market and after-hours data is available
- Timestamps are in ISO 8601 format (UTC)
- Maximum 50 symbols per request
