As a developer, APIs are the lifeblood of your applications—enabling you to fetch real-time data, power key features, and integrate services without having to reinvent the wheel. But not all APIs are created equal. Some are incredibly useful for free, while others pack a punch with their premium services.

Here's a curated list of the most valuable APIs in both categories—whether you're bootstrapping a side project or building the next big thing.

*Free APIs *

1. JSONPlaceholder
Use Case: Mocking API data
If you're tired of creating dummy endpoints while testing or developing, JSONPlaceholder has got your back. It provides ready-made, fake REST APIs for prototyping without having to spin up your own backend.

Free Tier: Entirely free for personal and professional use
Limitations: Mostly geared toward basic testing

2. Public APIs
Use Case: Just about everything
A treasure trove of free public APIs across various domains like weather, cryptocurrency, geolocation, and more. It's a curated list of open APIs, constantly updated to provide developers with an evolving resource hub.

Free Tier: Free forever
Limitations: Inconsistent data sources, some APIs may not have long-term support

3. OpenWeatherMap
Use Case: Weather data and forecasting
The go-to for any weather-based functionality in an app or website, providing real-time weather data, forecasting, and historical weather information.

Free Tier: 60 API calls per minute
Limitations: Lower call limits for free users, limited data granularity

4. PokeAPI
Use Case: Fun projects involving Pokémon
If you’re working on a playful project or want to mess around with data about Pokémon, PokeAPI is the way to go. A popular API among game devs and fans alike, it provides detailed data on every Pokémon, its moves, abilities, and more.

Free Tier: Completely free
Limitations: Limited to Pokémon data (great if you're into that)

5. Giphy API
Use Case: Embedding GIFs and stickers in apps
Who doesn’t love GIFs? Giphy’s API lets you integrate trending, relevant, or random GIFs and stickers into your app. Perfect for chat apps, social media platforms, or light-hearted projects.

Free Tier: 42 searches per hour
Limitations: Usage is capped, and the API is throttled at times

Paid APIs Worth the Investment

6. Twilio API
Use Case: SMS, voice, and video communications
If you're building anything that involves real-time communication (SMS alerts, verification codes, customer service calls, etc.), Twilio is your best bet. Their APIs for messaging and voice are incredibly reliable, scalable, and secure.

Paid Tier: Pay-as-you-go model (starts at $0.0075/SMS, $0.013/min voice call)
Limitations: Can get expensive if you scale up

7. Algolia Search API
Use Case: Advanced search functionality
Providing blazing fast, highly relevant search results, Algolia powers search for some of the biggest names in tech. Its features include typo tolerance, filters, synonyms, and real-time indexing, making it perfect for e-commerce, SaaS, and content-heavy applications.

Paid Tier: Starts at $1 per 1,000 search requests
Limitations: Free tier exists but very limited (10,000 operations/month)

8. Clearbit API
Use Case: Business intelligence and customer enrichment
Clearbit's suite of APIs can instantly enrich data by providing detailed information on companies, employees, and customers—ideal for sales, marketing, or SaaS tools that rely on accurate customer data.

Paid Tier: Custom pricing based on usage
Limitations: Can get expensive for smaller teams

9. Stripe API
Use Case: Payment processing
The standard for modern payment solutions, Stripe makes it super easy to integrate payments into your web and mobile apps. It supports global currencies, recurring payments, and even invoicing, making it an all-in-one solution for e-commerce.

Paid Tier: 2.9% + $0.30 per successful charge
Limitations: Free to start but takes a cut of every transaction

10. AWS Textract API
Use Case: Extracting text and data from documents
Amazon's Textract API uses machine learning to automatically extract text, tables, and even forms from scanned documents, making it invaluable for fintech, healthcare, and legal applications where documents are plentiful.

Paid Tier: Starts at $1.50 per 1,000 pages
Limitations: No free tier, but highly specialized

Let me know your favorite in the comments!