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# Introduction
You've probably heard people talk a lot about APIs. Basically, an API allows software to ask another piece of software for help. For example, if we use our weather app, it can use a real-time API to get data from a remote server. This small dialog saves you from having to build everything yourself. In this article, we'll take a look at five fun and incredibly easy-to-use APIs. You'll get to test AI models, web data, search engines, fine-tune models, and synthetic data. Each of these APIs opens up opportunities to learn, test, and build small projects without heavy setup. So, let's begin.
# 1. OpenRouter
When I was working on my research paper and needed to call many models of major languages, the biggest headache for me was keeping track of all the different API keys. I really wished there was access to all of them at once (problem exactly OpenRouter are resolved). An integrated API gateway for major language models that gives you access to more than 100 models from major providers such as OpenAI, Anthropic, Google, Meta, Mistral, Cohere, and many other open source methods. Therefore, you only need one API key and one integration, and you can switch between models by changing a parameter. It also handles intelligent supplier routing, automatic fallback if a model is down, and routing based on cost, delay, or availability. Responses come in a standard format (text or image support), support streaming via SSE, and all SDKs / clients compatible with OpenAI APIs (Python, JS, etc.) work out of the box with OpenRouter. Pricing is pay as you go and has no minimum, starting at fractions of a cent per token, and there is a free trial phase.
# 2. Olostep
I personally believe that the two biggest challenges of using LLMs are getting real-time data to ensure that your information is up-to-date and converted into a structured format that your model can actually use. Again Olostep solving both. A web data API that allows you to scrape, crawl, and search almost any publicly available website and get results quickly in the format you want. You can feed live search results, news, or other online content directly to your app. Olostep also takes care of data editing. It supports multiple endpoints, e.g./scrapes for individual URLs, /crawls repeatedly following links throughout the site, /batches processing thousands of URLs in parallel, and /answers allowing for “asking the web” style questions where you get extracted answers (with sources) rather than raw HTML. The API also handles pages translated with JavaScript, proxies, and anti-bot mechanisms automatically, making it reliable even on complex websites. Pricing starts at free (500 applications), with paid tiers from USD 9/month (5k applications) to USD 399/month (1M applications), and credit packs for flexibility.
# 3. Tinker API
The Tinker API a new API from Think Machines Lab (launched October 2025) that aims to facilitate fine-tuning and custom training of large open-weighted linguistic models by giving you full control over the training loop i.e. forward_backward, optim_step, sample, save_state etc. Once the training is complete, you can download the adapter/weights and use them outside of your favorite Tinker stack. It supports popular base models such as Llama, Mistral, and GPT variants, with LoRA/QLORA fine-tuning endpoints, multi-agent simulations, and data-centric tweaks such as artificial expansion or bias reduction. It also features a sandbox-like interface for prototyping in minutes. Tinker is currently in private beta with a free phase for small tests (eg, <1B parameters), and is already being used by research groups at universities such as Princeton, Stanford, and UC Berkeley. Scale in hourly billing models starting at USD 0.50/hour for mid-range GPUs.
# 4. SerpApi
SerpApi is a real-time web search API that makes it easy to get organized search results from Google and other search engines. It can download environmental results, news, images, shopping lists, maps, and infographic boxes, and deliver them in pure JSON (or raw HTML). The API handles complex components for you, including solving CAPTCHAs, rendering JavaScript, managing proxies, and simulating real user behavior, for accurate and up-to-date results. You can control many parameters, including search query, language, location, device type, search type, pagination, and output format. This makes it easy to fine-tune the data you receive. Pricing starts with a free tier that offers 250 searches per month. Paid plans include Developer at USD 75 for 5,000 searches, Productivity at USD 150 for 15,000 searches, and Big Data at USD 275 for 30,000 searches. All plans are month-to-month, with 99.95% uptime for premium options and high-volume custom plans are available.
# 5. MOST AI Generator API
MOST AI Generator API helps you create realistic, privacy-protected data from your real dataset. You start by training the generator on your tables, CSVs, or database. The generator learns patterns, correlations, and relationships in your data while keeping private information safe. After training, you can create as many new records as you need using the API or the Python SDK. It works with many types of data, including numbers, categories, text, time series, geolocation, and multi-table data sets. You can also perform conditional sampling, balance redistribution, or fill in missing values. The platform provides detailed reports to see how closely the synthetic data matches the original, including distribution and correlation. You can use this data to securely share across teams, test machine learning models, or run experiments where using real data is risky. It gives you actionable, flexible data you can trust for analytics, AI training, or research without exposing sensitive information.
# Wrapping up
These five APIs show how much you can do without building everything from scratch. OpenRouter makes working with multiple LLMs easy with a single API key. Olostep gives you live web data and converts it into a structured format that you can use for your models. Tinker lets you tune in and experiment with LLMs without complicated setup. SerpApi makes real-time search easy and reliable, and the MOST AI Generator API helps you create realistic, privacy-secure data for testing and evaluation. Each is powerful, but also beginner-friendly enough to give it a quick try.
Which APIs do you like the most? Have you tried any of these, or do you use others? Share your favorites in the comments below. I'd love to see what you're working on 🙂
Kanwal Mehreen is a machine learning engineer and technical writer with a deep passion for data science and the intersection of AI and medicine. He co-authored the ebook “Increasing Productivity with ChatGPT”. As a Google Generation Scholar 2022 for APAC, he strives for diversity and academic excellence. He has also been recognized as a Teradata Diversity in Tech Scholar, a Mitacs Globalink Research Scholar, and a Harvard WeCode Scholar. Kanwal is a passionate advocate for change, having founded FEMCodes to empower women in STEM fields.
