DEV Community: 이성열 (월억)

I Built a Free Tool to Compare Economies of 200+ Countries (World Bank API + Next.js)

이성열 (월억) — Fri, 27 Mar 2026 01:24:03 +0000

I wanted to compare South Korea and Japan's economies for a research project. Spent 30 minutes clicking around the World Bank website, trying to export data, struggling with their clunky interface.

So I built my own tool. In one day.

What I Built

CountryCompare — a free, interactive dashboard that lets you compare economic indicators between countries using World Bank data.

Try it: country-compare.com

What You Can Do

Compare 2 countries side by side (free) or up to 10 (Pro)
View 50 economic indicators across 6 categories: Economy, Labor, Society, Energy, Environment, Trade
See 25 years of historical data in interactive charts
Download PDF reports and CSV data
Browse 50 country profiles with key economic snapshots
Dark mode included

The Numbers

1,290 auto-generated pages (every country pair gets its own SEO-optimized page)
50 indicators from World Bank Open Data
50 country profiles
$0 hosting cost (Vercel free tier)
$0 data cost (World Bank API is free, no key required)

Tech Stack

Next.js 14 (App Router, TypeScript)
Chart.js + react-chartjs-2 for interactive charts
Tailwind CSS for styling + dark mode
Vercel for hosting (free tier)
World Bank API for data (free, no API key needed)

How the World Bank API Works

The World Bank API is surprisingly simple and completely free:

GET https://api.worldbank.org/v2/country/US;JP/indicator/NY.GDP.MKTP.CD?format=json&date=2000:2024&per_page=500

Breaking it down:

/country/US;JP — semicolon-separated ISO2 codes for multiple countries
/indicator/NY.GDP.MKTP.CD — the indicator code (this one is GDP in USD)
format=json — returns JSON instead of XML
date=2000:2024 — 25 years of data in one call

Here's the actual fetch function from my codebase:

const BASE_URL = 'https://api.worldbank.org/v2';

export async function fetchIndicator(
  countryCodes: string[],
  indicatorId: string
) {
  const codes = countryCodes.join(';');
  const url = `${BASE_URL}/country/${codes}/indicator/${indicatorId}?format=json&date=2000:2024&per_page=500`;

  const res = await fetch(url, { next: { revalidate: 86400 } }); // Cache 24h
  const json = await res.json();
  return json[1] || []; // [0] is metadata, [1] is actual data
}

No API key. No rate limits I've ever hit. No authentication. Just clean, free data for 200+ countries.

Key indicator codes I use:

Code	Indicator
`NY.GDP.MKTP.CD`	GDP (USD)
`NY.GDP.PCAP.CD`	GDP per Capita
`SP.POP.TOTL`	Population
`SL.UEM.TOTL.ZS`	Unemployment Rate
`FP.CPI.TOTL.ZG`	CPI Inflation
`SP.DYN.LE00.IN`	Life Expectancy
`EN.ATM.CO2E.PC`	CO2 per Capita
`SE.ADT.LITR.ZS`	Literacy Rate
`IT.NET.USER.ZS`	Internet Users %

The full app uses 50 indicators across 6 categories.

SEO Strategy: 1,290 Pages from 50 Countries

This is where it gets interesting. With 50 countries, you get C(50,2) = 1,225 unique comparison pairs. Add 50 country profile pages and some static pages, and you've got 1,290 indexable pages — all auto-generated at build time.

How It Works

// Generate all country-pair slugs
export function getAllCompareSlugs(): string[] {
  const slugs: string[] = [];
  for (let i = 0; i < COUNTRIES.length; i++) {
    for (let j = i + 1; j < COUNTRIES.length; j++) {
      slugs.push(`${COUNTRIES[i].slug}-vs-${COUNTRIES[j].slug}`);
    }
  }
  return slugs;
}

// Next.js static generation
export function generateStaticParams() {
  return getAllCompareSlugs().map((slug) => ({ slug }));
}

This generates URLs like:

/compare/united-states-vs-china
/compare/south-korea-vs-japan
/compare/germany-vs-france

Each page gets its own metadata and OG image:

export async function generateMetadata({ params }): Promise<Metadata> {
  return {
    title: `${countryA} vs ${countryB} - Economic Comparison`,
    openGraph: {
      images: [{
        url: `/api/og?a=${countryA}&b=${countryB}`,
        width: 1200,
        height: 630,
      }],
    },
  };
}

A dynamic sitemap feeds all 1,290 URLs to search engines with tiered priorities — homepage at 1.0, comparisons at 0.8, country profiles at 0.7.

Result: Every country pair is a long-tail keyword target. Someone Googling "USA vs China economy comparison" could land on a pre-built, data-rich page.

Free vs Pro

I wanted the core tool to be genuinely useful for free. Here's the split:

Feature	Free	Pro ($9/mo)
Indicators	5 (Overview)	50 (all categories)
Countries	Compare 2	Compare up to 10
Data Range	10 years (2014-2024)	25 years (2000-2024)
PDF Reports	Watermarked, 5 indicators	Full 50-indicator report
CSV Export	—	Included
Ads	Yes	No

The free tier gives you GDP, Population, Unemployment, Inflation, and Life Expectancy with 10 years of charts. That's enough for a quick comparison or school project.

Pro unlocks the deep dive: 50 indicators across Economy, Labor, Society, Energy, Environment, and Trade — plus multi-country comparison up to 10 countries on one chart.

Payment goes through Gumroad. License keys are verified server-side and stored as JWT tokens:

export function createToken(licenseKey: string): string {
  return jwt.sign(
    { licenseKey, pro: true },
    JWT_SECRET,
    { expiresIn: '7d' }
  );
}

What I Learned

1. The World Bank API is an underrated goldmine

Free, no auth, well-structured, 200+ countries, 1,400+ indicators. If you're building anything data-related, check it out before scraping Wikipedia.

2. Combinatorics is your SEO friend

50 countries × 49 partners ÷ 2 = 1,225 unique pages. Each one is a potential search result. generateStaticParams() in Next.js makes this trivial.

3. Build the free tier first, pro features second

I built the complete 2-country comparison with 5 indicators first. It worked. It was useful. Only then did I add the paywall for power features. This keeps you honest about whether the core product has value.

4. Dark mode is table stakes in 2025

I almost skipped it. Glad I didn't. The implementation is straightforward with Tailwind's dark: prefix + a localStorage toggle + a script in <head> to prevent flash:

<script dangerouslySetInnerHTML={{ __html: `(function(){
  try {
    var t = localStorage.getItem('theme');
    if (t === 'dark' || (!t && window.matchMedia('(prefers-color-scheme:dark)').matches)) {
      document.documentElement.classList.add('dark');
    }
  } catch(e) {}
})()`}} />

5. PDF generation on the server is worth the effort

Using jspdf + jspdf-autotable on a Next.js API route means users get a clean, branded PDF without any client-side library loading. The Pro report generates a cover page, executive summary, and one data table per indicator — up to 50 pages of data.

Try It Out

Live site: country-compare.com
Example comparison: US vs China
Country profile: South Korea

The free tier is fully functional — compare any 2 countries across 5 key indicators with interactive charts, right now.

Feedback welcome. What indicators or features would you want to see added?

Built in one day with Next.js, Chart.js, Tailwind CSS, and the World Bank API. Hosted for free on Vercel.

Energy Import Korea Japan Oil Data Update — Trends, Analysis & API Access

이성열 (월억) — Sat, 21 Mar 2026 04:26:12 +0000

The latest data from the Federal Reserve (FRED) shows Energy Import Korea Japan Oil at 333.5Index 1982-1984=100 — ▲ 0.72Index 1982-1984=100 from the previous period. Here's what the numbers actually mean, and how to access them programmatically.

📊 Recent Trend

Month	Consumer Price Index For All U
2025-06	327.658Index 1982-1984=100
2025-07	328.682Index 1982-1984=100
2025-08	329.700Index 1982-1984=100
2025-09	330.418Index 1982-1984=100
2025-11	331.043Index 1982-1984=100
2025-12	331.814Index 1982-1984=100
2026-01	332.793Index 1982-1984=100
2026-02	333.512Index 1982-1984=100

🔍 What This Means

1. Context matters
A single data point rarely tells the full story. Looking at the 12-month trend reveals whether we're seeing a temporary blip or a structural shift. The data above shows the gradual movement over recent months.

2. Watch the broader indicators
The headline number is just one piece of the puzzle. Cross-referencing with related indicators gives a more complete picture of what's really happening in the economy.

3. Data-driven decisions
Whether you're a developer building financial tools, a researcher tracking trends, or a business making strategic decisions — having clean, structured access to this data makes all the difference.

📈 All Key Indicators

Indicator	Latest	Change
Consumer Price Index For All U	333.5Index 1982-1984=100	▲ 0.72Index 1982-1984=100
Crude Oil Prices: West Texas I	93.4$ per Barrel	▼ 5.09$ per Barrel
Crude Oil Prices: Brent - Euro	101.0$ per Barrel	▼ 2.19$ per Barrel

💻 Access the Data as a Developer

Pull this data directly via API in seconds:

import requests

url = "https://energy-import-korea-japan-oil.vercel.app/summary"
response = requests.get(url, params={"limit": 12})
data = response.json()

for entry in data["data"]["consumer_price_index_for_all_u"]:
    print(entry["date"], entry["value"])

Output:

2026-02-01  333.512
2026-01-01  332.793
2025-12-01  331.814
2025-11-01  331.043
...

Available Endpoints

Endpoint	Description
`/summary`	Key indicators overview
`/current`	Latest reading only
`/history`	Full historical series

Pricing

Plan	Price	Requests/month
BASIC	Free	100
PRO	$9/mo	10,000
ULTRA	$29/mo	50,000

Get API Access on RapidAPI →

📺 Video Walkthrough

Data source: FRED (Federal Reserve Bank of St. Louis). Updated daily. Built with GlobalData Store API.

Energy Import Korea Japan Oil Data Data Update — Trends, Analysis & API Access

이성열 (월억) — Sat, 21 Mar 2026 04:19:58 +0000

The latest data from the Federal Reserve (FRED) shows Energy Import Korea Japan Oil Data at 333.5Index 1982-1984=100 — ▲ 0.72Index 1982-1984=100 from the previous period. Here's what the numbers actually mean, and how to access them programmatically.

📊 Recent Trend

Month	Consumer Price Index For All U
2025-06	327.658Index 1982-1984=100
2025-07	328.682Index 1982-1984=100
2025-08	329.700Index 1982-1984=100
2025-09	330.418Index 1982-1984=100
2025-11	331.043Index 1982-1984=100
2025-12	331.814Index 1982-1984=100
2026-01	332.793Index 1982-1984=100
2026-02	333.512Index 1982-1984=100

🔍 What This Means

📈 All Key Indicators

Indicator	Latest	Change
Consumer Price Index For All U	333.5Index 1982-1984=100	▲ 0.72Index 1982-1984=100
Crude Oil Prices: West Texas I	93.4$ per Barrel	▼ 5.09$ per Barrel
Crude Oil Prices: Brent - Euro	101.0$ per Barrel	▼ 2.19$ per Barrel

💻 Access the Data as a Developer

Pull this data directly via API in seconds:

import requests

url = "https://energy-import-korea-japan-oil-data.vercel.app/summary"
response = requests.get(url, params={"limit": 12})
data = response.json()

for entry in data["data"]["consumer_price_index_for_all_u"]:
    print(entry["date"], entry["value"])

Output:

2026-02-01  333.512
2026-01-01  332.793
2025-12-01  331.814
2025-11-01  331.043
...

Available Endpoints

Endpoint	Description
`/summary`	Key indicators overview
`/current`	Latest reading only
`/history`	Full historical series

Pricing

Plan	Price	Requests/month
BASIC	Free	100
PRO	$9/mo	10,000
ULTRA	$29/mo	50,000

Get API Access on RapidAPI →

📺 Video Walkthrough

Data source: FRED (Federal Reserve Bank of St. Louis). Updated daily. Built with GlobalData Store API.

Us Unemployment Data Update — Trends, Analysis & API Access

이성열 (월억) — Sat, 21 Mar 2026 02:52:42 +0000

The latest data from the Federal Reserve (FRED) shows Us Unemployment at 4.4% — ▲ 0.10% from the previous period. Here's what the numbers actually mean, and how to access them programmatically.

📊 Recent Trend

Month	Unemployment Rate
2025-07	4.3%
2025-08	4.3%
2025-09	4.4%
2025-11	4.5%
2025-12	4.4%
2026-01	4.3%
2026-02	4.4%

🔍 What This Means

📈 All Key Indicators

Indicator	Latest	Change
Unemployment Rate	4.4%	▲ 0.10%
U6 Rate	7.9%	▼ 0.20%
Youth Unemployment	14.9	▲ 1.30
Longterm Unemployment	4.5	▲ 0.16

💻 Access the Data as a Developer

Pull this data directly via API in seconds:

import requests

url = "https://us-unemployment-api.vercel.app/summary"
response = requests.get(url, params={"limit": 12})
data = response.json()

for entry in data["data"]["unemployment_rate"]:
    print(entry["date"], entry["value"])

Output:

2026-02-01  4.4
2026-01-01  4.3
2025-12-01  4.4
2025-11-01  4.5
...

Available Endpoints

Endpoint	Description
`/summary`	Key indicators overview
`/current`	Latest reading only
`/history`	Full historical series

Pricing

Plan	Price	Requests/month
BASIC	Free	100
PRO	$9/mo	10,000
ULTRA	$29/mo	50,000

Get API Access on RapidAPI →

📺 Video Walkthrough

Data source: FRED (Federal Reserve Bank of St. Louis). Updated daily. Built with GlobalData Store API.

Us Unemployment Data Update — Trends, Analysis & API Access

이성열 (월억) — Sat, 21 Mar 2026 02:32:31 +0000

📊 Recent Trend

Month	Unemployment Rate
2025-07	4.3%
2025-08	4.3%
2025-09	4.4%
2025-11	4.5%
2025-12	4.4%
2026-01	4.3%
2026-02	4.4%

🔍 What This Means

📈 All Key Indicators

Indicator	Latest	Change
Unemployment Rate	4.4%	▲ 0.10%
U6 Rate	7.9%	▼ 0.20%
Youth Unemployment	14.9	▲ 1.30
Longterm Unemployment	4.5	▲ 0.16

💻 Access the Data as a Developer

Pull this data directly via API in seconds:

import requests

url = "https://us-unemployment-api.vercel.app/summary"
response = requests.get(url, params={"limit": 12})
data = response.json()

for entry in data["data"]["unemployment_rate"]:
    print(entry["date"], entry["value"])

Output:

2026-02-01  4.4
2026-01-01  4.3
2025-12-01  4.4
2025-11-01  4.5
...

Available Endpoints

Endpoint	Description
`/summary`	Key indicators overview
`/current`	Latest reading only
`/history`	Full historical series

Pricing

Plan	Price	Requests/month
BASIC	Free	100
PRO	$9/mo	10,000
ULTRA	$29/mo	50,000

Get API Access on RapidAPI →

📺 Video Walkthrough

Data source: FRED (Federal Reserve Bank of St. Louis). Updated daily. Built with GlobalData Store API.

Us Unemployment Data Update — Trends, Analysis & API Access

이성열 (월억) — Sat, 21 Mar 2026 02:21:10 +0000

📊 Recent Trend

Month	Unemployment Rate
2025-07	4.3%
2025-08	4.3%
2025-09	4.4%
2025-11	4.5%
2025-12	4.4%
2026-01	4.3%
2026-02	4.4%

🔍 What This Means

📈 All Key Indicators

Indicator	Latest	Change
Unemployment Rate	4.4%	▲ 0.10%
U6 Rate	7.9%	▼ 0.20%
Youth Unemployment	14.9	▲ 1.30
Longterm Unemployment	4.5	▲ 0.16

💻 Access the Data as a Developer

Pull this data directly via API in seconds:

import requests

url = "https://us-unemployment-api.vercel.app/summary"
response = requests.get(url, params={"limit": 12})
data = response.json()

for entry in data["data"]["unemployment_rate"]:
    print(entry["date"], entry["value"])

Output:

2026-02-01  4.4
2026-01-01  4.3
2025-12-01  4.4
2025-11-01  4.5
...

Available Endpoints

Endpoint	Description
`/summary`	Key indicators overview
`/current`	Latest reading only
`/history`	Full historical series

Pricing

Plan	Price	Requests/month
BASIC	Free	100
PRO	$9/mo	10,000
ULTRA	$29/mo	50,000

Get API Access on RapidAPI →

Data source: FRED (Federal Reserve Bank of St. Louis). Updated daily. Built with GlobalData Store API.

Us Unemployment Data Update — Trends, Analysis & API Access

이성열 (월억) — Sat, 21 Mar 2026 02:11:42 +0000

📊 Recent Trend

Month	Unemployment Rate
2025-07	4.3%
2025-08	4.3%
2025-09	4.4%
2025-11	4.5%
2025-12	4.4%
2026-01	4.3%
2026-02	4.4%

🔍 What This Means

📈 All Key Indicators

Indicator	Latest	Change
Unemployment Rate	4.4%	▲ 0.10%
U6 Rate	7.9%	▼ 0.20%
Youth Unemployment	14.9	▲ 1.30
Longterm Unemployment	4.5	▲ 0.16

💻 Access the Data as a Developer

Pull this data directly via API in seconds:

import requests

url = "https://us-unemployment-api.vercel.app/summary"
response = requests.get(url, params={"limit": 12})
data = response.json()

for entry in data["data"]["unemployment_rate"]:
    print(entry["date"], entry["value"])

Output:

2026-02-01  4.4
2026-01-01  4.3
2025-12-01  4.4
2025-11-01  4.5
...

Available Endpoints

Endpoint	Description
`/summary`	Key indicators overview
`/current`	Latest reading only
`/history`	Full historical series

Pricing

Plan	Price	Requests/month
BASIC	Free	100
PRO	$9/mo	10,000
ULTRA	$29/mo	50,000

Get API Access on RapidAPI →

Data source: FRED (Federal Reserve Bank of St. Louis). Updated daily. Built with GlobalData Store API.

Us Unemployment Data Update — Trends, Analysis & API Access

이성열 (월억) — Sat, 21 Mar 2026 01:33:15 +0000

📊 Recent Trend

Month	Unemployment Rate
2025-07	4.3%
2025-08	4.3%
2025-09	4.4%
2025-11	4.5%
2025-12	4.4%
2026-01	4.3%
2026-02	4.4%

🔍 What This Means

📈 All Key Indicators

Indicator	Latest	Change
Unemployment Rate	4.4%	▲ 0.10%
U6 Rate	7.9%	▼ 0.20%
Youth Unemployment	14.9	▲ 1.30
Longterm Unemployment	4.5	▲ 0.16

💻 Access the Data as a Developer

Pull this data directly via API in seconds:

import requests

url = "https://us-unemployment-api.vercel.app/summary"
response = requests.get(url, params={"limit": 12})
data = response.json()

for entry in data["data"]["unemployment_rate"]:
    print(entry["date"], entry["value"])

Output:

2026-02-01  4.4
2026-01-01  4.3
2025-12-01  4.4
2025-11-01  4.5
...

Available Endpoints

Endpoint	Description
`/summary`	Key indicators overview
`/current`	Latest reading only
`/history`	Full historical series

Pricing

Plan	Price	Requests/month
BASIC	Free	100
PRO	$9/mo	10,000
ULTRA	$29/mo	50,000

Get API Access on RapidAPI →

📺 Video Walkthrough

Data source: FRED (Federal Reserve Bank of St. Louis). Updated daily. Built with GlobalData Store API.

📊 Us Unemployment API — Real-time Economic Data 2026

이성열 (월억) — Sat, 21 Mar 2026 01:24:31 +0000

Us Unemployment — Real-time Economic Data

Latest Data

About This API

Us Unemployment provides real-time, structured economic data sourced directly from official databases including FRED (Federal Reserve), World Bank, and IMF.

Key Features

Updated daily with official data
Clean JSON format — ready to use
REST API with simple authentication
Multiple endpoints: /summary, /series, /latest

Quick Start

curl -X GET "https://us-unemployment-api.vercel.app/summary?limit=12" \
  -H "x-rapidapi-key: YOUR_API_KEY" \
  -H "x-rapidapi-host: us-unemployment-api.p.rapidapi.com"

Response Example

{
  "data": {
    "unemployment_rate": [
      {"date": "2026-01-01", "value": "4.4"},
      {"date": "2025-10-01", "value": "4.3"}
    ]
  },
  "updated_at": "2026-03-01"
}

Pricing

Plan	Price	Requests/month
BASIC	Free	100
PRO	$9/mo	10,000
ULTRA	$29/mo	50,000

👉 Get API Access on RapidAPI

GlobalData Store — 100+ economic data APIs covering US, Korea, Japan, EU, China, and Global markets.

data #api #economics #finance