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 - Apple
• GOOGL - Alphabet (Google)
• META - Meta (Facebook)
• AMZN - Amazon
• NFLX - Netflix
• MSFT - Microsoft

High-Profile Stocks

• NVDA - NVIDIA
• TSLA - Tesla
• AMD - Advanced Micro Devices
• INTC - Intel
• ORCL - Oracle

Indices

• ^GSPC - S&P 500
• ^DJI - Dow Jones
• ^IXIC - NASDAQ

Notes

• Response format: API returns TOON, not JSON. Use decode() from @toon-format/toon to 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