Open data is one of the quiet advantages of modern analytics. Governments, research institutions, and nonprofits publish enormous, freely usable datasets, and most teams never tap them. Used well, open data feeds trend analysis, measures the effect of public policy, sharpens product decisions, and grounds a model in real numbers instead of guesses.
This guide collects strong, genuinely free open data sources, grouped by subject so you can jump to what your project needs: economic and financial, government, health, science, academic, environmental, crime, business directory, media, social, and a few catch-all repositories. For each one you get what it provides and how people typically use it. After the list, you will find free public data sources matched to app ideas, a quick way to turn a dataset into an app, and a short note on using open data responsibly.
What is open data?
Open data is data that anyone can access, use, and share without paying for it or asking special permission. In practice that rests on three ideas. Anyone can access it, so the files are public rather than locked behind a rejected request or a long-dead format. Anyone can use it, so individuals, companies, and governments may build on it freely, and it excludes the sensitive personal information that should never be public. Anyone can share it, so the data can be reused and redistributed.
Government agencies and nonprofit organizations host most of it, because storing and serving data at scale is expensive and they already do it as part of their mission. Much of it carries a license such as Creative Commons, which lets you use the data freely while telling you how to credit the source. That license is the part most people skip, and it is the part that keeps your use clean, so read it before you build on a dataset.
Economic and financial data
Markets, trade flows, and macroeconomic indicators, useful for research, dashboards, and anything that needs a reliable baseline of numbers.
Global Financial Data
GFD offers free subscriptions that open up global market and economic data, alongside periodicals, books, and a deep archive of historical series. It is a good starting point when you need long time horizons rather than just recent figures.
U.N. Comtrade Database
Curated by Comtrade Labs, this free database covers global trade and exposes it through an API, so you can pull figures programmatically instead of downloading spreadsheets by hand. It also bundles tools for visualizing and extracting the data.
World Bank Open Data
One of the best single sources for GDP, logistics, global energy consumption, and the disbursement and management of global funds. It is updated frequently, and some datasets ship with their own visualization tools.
Financial Times
Though it presents as an online newspaper, the Financial Times is also a broad source of information on global markets across the Americas, Europe, Africa, and Asia, which makes it useful for qualitative context around the raw numbers.
Government and global data
National statistics offices and intergovernmental bodies publish some of the richest open data anywhere, covering everything from crime to demographics.
Data.gov.uk
The UK counterpart to the United States data.gov, spanning categories from crime and justice to defense and government spending. A practical first stop for anyone working with British public data.
U.K. Data Service
A complement to Data.gov.uk with recent datasets on social trends, politics, finance, and international relations, aimed more at the research community.
Open Data Network
A search engine for open datasets, with advanced filters that help you find public safety, finance, infrastructure, housing, and development data quickly rather than browsing site by site.
UNICEF
Open datasets that monitor and report on children and women worldwide, including disease outbreaks, gender and education, and attitudes toward social norms.
Data.gov
One of the most comprehensive open data portals in the world, covering science and research through to manufacturing and climate. Data comes in CSV, JSON, and XML, and the metadata is updated frequently so you can trust that what you pull is current. If you plan to load it into a spreadsheet or database, our notes on JSON versus CSV help you pick the right format.
U.S. Census Bureau
The definitive open source for demographic data on U.S. residents, assembled from federal, state, and local governments plus private companies. Indispensable for population, housing, and economic demography work.
Health data
Public health agencies and research institutes publish detailed health datasets, valuable to researchers, policymakers, and anyone building tools in the health space.
HealthData.gov
A repository of more than 3,000 datasets spanning over 125 years, built to give entrepreneurs, researchers, and policymakers access to high-value health data.
Broad Institute
A clear, well-organized source of open health and scientific research data, with particular depth on various cancers.
Food and Drug Administration
The FDA publishes data on foodborne illnesses and contaminants, recalls, and news about dietary supplements in the United States.
National Cancer Institute
Part of the National Institutes of Health and a complement to the Broad Institute, with advanced filters that let you narrow in on specific cancer-related datasets.
World Health Organization
One of the most comprehensive global repositories for mortality rates, disease outbreaks, mental illness, and health financing.
Center for Disease Control
The CDC offers a wide range of free datasets on chronic illness, cancer, heart disease, congenital conditions, and much more.
NHS Digital
An easy-to-use free service providing high-quality datasets on the state of health and social care systems in England.
Scientific data
Earth, space, and cross-disciplinary research data, often at very large scale.
NASA Earth Data
Free Earth science data from NASA, with measurements across the atmosphere, the cryosphere, land, the ocean, and the calibrated radiance of the sun.
Open Science Data Cloud
OSDC holds more than a petabyte of large datasets and lets scientific researchers manage, share, and analyze open data efficiently across many disciplines.
NASA Planetary Data System
Thousands of open datasets about the planets in our solar system, available to researchers, educators, students, and the general public alike.
Academic data
Education statistics, survey research, and scholarly work, useful for institutions, social scientists, and literature reviews.
National Center for Education Statistics
The NCES publishes datasets that educational institutions use to improve retention and graduation rates and to understand how students learn.
Pew Research Center
One of the country's largest open data sources, aggregating high-quality survey datasets. Survey data is typically released two years after the report is published, and you create a free account to access it.
Google Scholar
Searching for datasets here works much like a normal search engine, giving you a wide pool of educational, peer-reviewed sources to draw on.
Environmental data
Energy, climate, and environmental health datasets for sustainability research and reporting.
IEA Atlas of Energy
Open datasets from the International Energy Agency that let you view global consumption rates for energy and electricity.
Climate Data Online
CDO is a strong source for historical and near-real-time climate data worldwide, including daily summaries, marine data, and weather radar.
National Center for Environmental Health
Curated by the CDC, this repository highlights national data systems that collect public health and environmental data from a country-wide perspective.
Many of these portals expose APIs, but plenty of useful public data still lives on ordinary web pages that render with JavaScript or rate-limit heavy traffic. When the source is a site rather than a clean download, the Crawlbase Crawling API requests the page for you and returns the HTML, handling JavaScript rendering, IP rotation, and CAPTCHAs so collection does not stall. You keep your own parsing code and start with up to 5,000 free requests.
Crime and drug data
Criminal justice and substance-abuse datasets, mostly from U.S. federal agencies and the United Nations.
National Archive of Criminal Justice Data
The NACJD provides public and restricted-access datasets on recidivism, gang violence, terrorism, hate crimes, and more.
National Institute on Drug Abuse
NIDA hosts datasets significant to anyone studying tobacco, alcohol, illicit drugs, and prescription opioid abuse in the United States.
Uniform Crime Reporting Program
The FBI aggregates statistics from more than 18,000 cities, colleges, counties, states, and tribes through this program.
Bureau of Justice Statistics
Beyond arrest-related deaths, the BJS collects figures such as annual emergency room data and firearm inquiries.
United Nations Office on Drugs and Crime
The UNODC regularly publishes datasets on drug production and trafficking, homicide rates, corruption, and organized crime.
Business directory data
Company records and review data, useful for market research, competitive analysis, and lead generation.
Open Corporates
One of the world's largest open company databases, with hundreds of millions of corporate records across virtually every country.
Glassdoor
Job-review sites carry a surprising amount of open data. On Glassdoor you can find gender pay analysis, monthly salary reports, and local pay reports.
Yelp
Yelp's open datasets contain millions of business reviews, which you can analyze to surface patterns and trends in business sentiment.
Media and journalism data
News archives and data-journalism sources, often available through developer APIs.
Associated Press Developer
The AP's developer services let you build integrations around news content, polling data, and metadata, in a similar spirit to the New York Times developer network.
FiveThirtyEight
A widely respected data-journalism source covering topics as varied as politics and sports, with datasets that back its published analysis.
The New York Times Developer Network
Register an app and you can access NYT abstracts, links, multimedia, books, listings, and stories, with text reaching as far back as 1851.
Marketing and social media data
Real-time sentiment, search interest, and social-graph data for marketers and analysts.
Social Mention
A search engine for real-time social data, surfacing sentiment, keyword usage, users, and hashtags at a broad scale.
Google Trends
Google Trends shows what the world is searching for, which lets marketers time campaigns around rising interest rather than guessing.
Graph API
The Graph API is a set of APIs that let apps read and write data from the Facebook social graph. Treat it as a structured window into public Facebook data, and note that its access is governed by Facebook's own terms.
Other repositories and aggregators
Catch-all sources that consolidate many of the datasets above and a few unusual ones.
Google Public Data Explorer
Many of the sources on this list are consolidated here, which makes it an excellent place to start when you are not sure where to look. Google Dataset Search complements it as a free way to find datasets across the web.
Datasets SubReddit
A Reddit community where people share interesting datasets, often scraped or compiled in languages such as R, useful for finding off-the-beaten-path data.
DBpedia
Think of Wikipedia as a database rather than a website. DBpedia lets you explore millions of Wikipedia entries and the relationships between them through a single query interface, which is why it has underpinned AI projects at companies including Apple, Google, and IBM.
Free public data sources for app ideas
Many of the sources above work as the backbone of an app, not just a report. What makes a source app-friendly is an API or regular bulk export, data that keeps updating, and a license that allows your use. The table pairs common app ideas with free sources that meet those tests, including a few developer-focused APIs that sit outside the main list.
| App idea | Free data source | How you get the data |
|---|---|---|
| Weather alerts or a local forecast app | National Weather Service API (api.weather.gov) | Free JSON API with no fees. Send a User-Agent that identifies your app, and stay within its rate limits. |
| Nutrition or calorie tracker | USDA FoodData Central | REST API with a free data.gov key. The data is public domain under CC0, and USDA asks you to credit FoodData Central. |
| Barcode food scanner | Open Food Facts | API for lookups plus nightly bulk exports. Licensed under the ODbL, so credit the source and share alike. |
| Maps, local search, or routing | OpenStreetMap | Open data under the ODbL. Credit OpenStreetMap and its contributors, and share derived databases under the same license. |
| Transit or commute app | Mobility Database | Open catalog of GTFS, GTFS Realtime, and GBFS feeds for transit and shared mobility, with an API. Feeds come from individual operators, so check each feed's terms. |
| Neighborhood or demographics dashboard | U.S. Census Bureau data API | Built for web and mobile apps, with a free API key on request. |
| Space and astronomy app | NASA Open APIs (api.nasa.gov) | Several NASA APIs behind one free api.data.gov key. |
| Book discovery or reading tracker | Open Library | JSON APIs and full data dumps, meant for open or mission-aligned book discovery apps. Read its usage guidelines and use the dumps for bulk work. |
| Machine learning prototype | Kaggle Datasets and the Awesome Public Datasets list on GitHub | Kaggle hosts community datasets next to example notebooks. Awesome Public Datasets is a topic-centric list that notes most, but not all, entries are free. Check each dataset's license. |
How to turn a public dataset into an app idea
A dataset is only a starting point. These checks tell you quickly whether it can carry an app.
- Start from a question people repeat. "Is my train late?", "What is in this snack?", "Will it rain at 5 p.m.?" An app answers one question faster than the source site does.
- Check freshness. A one-off research release suits an analysis or a data story. A live app needs a source that updates daily or in real time, like weather or transit feeds.
- Check access. Note whether you need an API key, what the rate limits are, and whether a bulk download exists for caching so you do not call the API on every page view.
- Check the license against your plan. Public domain and CC0 data carry the fewest conditions. Share-alike licenses such as the ODbL affect databases you build from the data, and some sources restrict commercial use.
- Combine two sources. The most useful ideas often join datasets, such as transit stops with weather or nutrition data with barcode lookups, which is harder for others to copy.
- Plan for gaps. If the public data you need only appears on web pages, collect it politely and within the site's terms, and prefer an official API the moment one exists.
Is big data open source?
A growing share of big-data tooling is open source, including database systems such as MongoDB, a scalable NoSQL store well suited to big-data workloads. Open-source components also cover the rest of the pipeline, from data collection and ingestion through processing and storage, so you can assemble a full stack without proprietary licensing. Open tools and open data pair naturally: free datasets give you the input, and open-source systems give you somewhere to put it.
Using open data responsibly
Free does not mean unconditional. Most open datasets carry a license, often Creative Commons, that tells you how you may use the data and how to credit the source, so read it and attribute correctly. When a source exposes an API, prefer it over scraping the site and stay within its rate limits and terms. If a dataset touches personal information, handle it under rules like GDPR and CCPA even when the data is technically public. When you collect from web pages rather than downloads, keep your request rate reasonable and respect each site's robots.txt. The goal is to be a good citizen of the open-data commons you are benefiting from. Once the data is in hand, our guides on structuring and cleaning data and analyzing it with pandas help you turn raw files into insight.
Key takeaways
- Open data is access, use, and share. A dataset counts as open when anyone can reach it, build on it, and redistribute it freely, usually under a license such as Creative Commons.
- Start from the category you need. Economic, government, health, science, academic, environmental, crime, business, media, and social each have established free sources, so pick the group before the source.
- Government and intergovernmental portals are the backbone. Data.gov, the U.S. Census Bureau, the World Bank, the WHO, and similar bodies publish some of the deepest, best-maintained open data anywhere.
- Aggregators save discovery time. Google Public Data Explorer, Google Dataset Search, and DBpedia consolidate many sources, which is the fastest way in when you do not know where to look.
- Respect the license and the rules. Read the license, attribute the source, prefer APIs over scraping, and apply privacy law when personal data is involved.
Frequently Asked Questions (FAQs)
What is the difference between open data and free data?
All open data is free to obtain, but open data goes further: it must also be free to reuse and redistribute, usually under an explicit license. Some data is free to view yet restricted in how you may use or share it, so check the license rather than assuming that free means open.
Which open data source should I start with?
Start from your subject. For broad U.S. government data, Data.gov is the natural entry point; for global economics, the World Bank; for demographics, the U.S. Census Bureau; for health, the WHO or HealthData.gov. If you are unsure where to look, Google Public Data Explorer and Google Dataset Search aggregate many sources in one place.
Can I use open data in a commercial product?
Often yes, but it depends entirely on the license attached to the specific dataset. Many open licenses, including most Creative Commons variants, permit commercial use as long as you attribute the source correctly. Always read the license terms for each dataset before shipping anything built on it.
Do I need to scrape open data or can I download it?
Most major portals offer direct downloads in CSV, JSON, or XML, or an API, and those should always be your first choice. Scraping only comes into play when useful public data lives on web pages with no download or API. In that case, collect it politely and within the site's terms.
Is big data the same as open data?
No. Big data describes the scale and complexity of datasets, while open data describes their licensing and accessibility. A dataset can be open without being large, and large datasets are frequently proprietary. They overlap when a big dataset is also published openly, as several sources on this list are.
Where can I find free public data sources for app ideas?
Start with sources that offer an API and update often. The National Weather Service API, USDA FoodData Central, Open Food Facts, OpenStreetMap, the Mobility Database for transit feeds, the U.S. Census Bureau data API, and NASA's Open APIs are all free to use under their own terms. For broader browsing, Data.gov, Kaggle Datasets, Google Dataset Search, and the Awesome Public Datasets list on GitHub cover thousands of topics.
Is public data free to use?
Public data is usually free to access, but how you may use it depends on its license. U.S. federal data such as USDA FoodData Central is often public domain, while sources like OpenStreetMap and Open Food Facts use the ODbL, which requires attribution and share-alike for derived databases. Some datasets are free to view but limit commercial reuse, so read the license before you ship an app built on it.
How do I keep my open data use compliant?
Read and follow each dataset's license, attribute the source as it requires, prefer official APIs over scraping, and respect rate limits and robots.txt when you do collect from pages. If the data includes personal information, handle it under applicable privacy laws such as GDPR and CCPA even though the data is public.
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