Many requests have come in regarding “training datasets” – to practice programming. Fortunately, the internet is full of open-source datasets! I compiled a selected list of datasets and repositories below. If you have any additions, please comment or contact me! For information on programming languages or algorithms, visit the overviews for RPython, SQL, or Data Science, Machine Learning, & Statistics resources.

LAST UPDATED: 12-02-2018
A Million News Headlines: News headlines published over a period of 14 years.
AggData | Datasets
Aligned Hansards of the 36th Parliament of Canada
Amazon Web Services: Public Datasets
American Community Survey
ArcGIS Hub Open Data
arXiv.org help – arXiv Bulk Data Access – Amazon S3
Asset Macro: Financial & Macroeconomic Historical Data
Awesome JSON Datasets
Awesome Public Datasets
Behavioral Risk Factor Surveillance System
British Oceanographic Data Center
Bureau of Justice
Canada
Causality | Data Repository
CDC Wonder Online Database
Census Bureau Home Page
Center for Disease Control
ChEMBLdb
ChemDB
City of Chicago
Click Dataset | Center for Complex Networks and Systems Research
CommonCrawl 2013 Web Crawl
Consumer Finance: Mortgage Database
CRCNS – Collaborative Research in Computational Neuroscience
Data Download
Data is Plural
Data.gov
Data.gov.au
Data.gov.nz
Data.gov.sg
Data.gov.uk
Data.Seattle.Gov | Seattle’s Data Site
Data.world
Data.World datasets
DataHub
Datasets for Data Mining
DataSF
Dataverse
DELVE datasets
DMOZ open directory (mirror)
DRYAD
Enigma Public
Enron Email Dataset
European Environment Agency (EEA) | Data and maps
Eurostat
Eurostat Database
Eurovision YouTube Comments: YouTube comments on entries from the 2003-2008 Eurovision Song Contests
FAA Data
Face Recognition Homepage – Databases
FAOSTAT Data
FBI Crime Data Explorer
FEMA Data Feeds
Figshare
FiveThirthyEight.com
Flickr personal taxonomies
FlowingData
Fraudulent E-mail Corpus: CLAIR collection of “Nigerian” fraud emails
Freebase (last datadump)
Gapminder.org
Gene Expression Omnibus (GEO) Main page
GeoJSON files for real-time Virginia transportation data.
Golem Dataset
Google Books n-gram dataset
Google Public Data Explorer
Google Research: A Web Research Corpus Annotated with Freebase Concepts
Health Intelligence
Healthcare Cost and Utilization Project
HealthData.gov
Human Fertility Database
Human Mortality Database
ICPRS Social Science Studies 
ICWSM Spinnr Challenge 2011 dataset
IIE.org Open Doors Data Portal
ImageNet
IMDB dataset
IMF Data and Statistics
Informatics Lab Open Data
Inside AirBnB
Internet Archive: Digital Library
IPUMS
Ironic Corpus: 1950 sentences labeled for ironic content
Kaggle Datasets
KAPSARC Energy Data Portal
KDNuggets Datasets
Knoema
Lahman’s Baseball Database
Lending Club Loan Data
Linking Open Data
London Datastore
Makeover Monday
Medical Expenditure Panel Survey
Million Song Dataset | scaling MIR research
MLDATA | Machine Learning Dataset Repository
MLvis Scientific Data Repository
MovieLens Data Sets | GroupLens Research
NASA
NASA Earth Data
National Health and Nutrition Examination Survey
National Hospital Ambulatory Medical Care Survey Data
New York State
NYPD Crash Data Band-Aid
ODI Leeds
OECD Data
OECD.Stat
Office for National Statistics
Old Newspapers: A cleaned subset of HC Corpora newspapers
Open Data Inception Portals
Open Data Nederland
Open Data Network
OpenDataSoft Repository
Our World in Data
Pajek datasets
PermID from Thomson Reuters
Pew Research Center
Plenar.io
PolicyMap
Princeton University Library
Project Gutenberg
Quandl
re3data.org
Reddit Datasets
Registry of Research Data Repositories
Retrosheet.org
Satori OpenData
SCOTUS Opinions Corpus: Lots of Big, Important Words
Sharing PyPi/Maven dependency data « RTFB
SMS Spam Collection
Socrata
St. Louis Federal Reserve
Stanford Large Network Dataset Collection
State of the Nation Corpus (1990 – 2017): Full texts of the South African State of the Nation addresses
Statista
Substance Abuse and Mental Health Services Administration 
Swiss Open Government Data
Tableau Public
The Association of Religious Data Archives
The Economist
The General Social Survey
The Huntington’s Early California Population Project
The World Bank | Data
The World Bank Data Catalog
Toronto Open Data
Translation Task Data
Transport for London
Twitter Data 2010
Ubuntu Dialogue Corpus: 26 million turns from natural two-person dialogues
UC Irvine Knowledge Discovery in Databases Archive
UC Irvine Machine Learning Repository –
UC Irvine Network Data Repository
UN Comtrade Database
UN General Debates:Transcriptions of general debates at the UN from 1970 to 2016
UNdata
Uniform Crime Reporting
UniGene
United States Exam Data
University of Michigan ICPSR
University of Rochester LibGuide “Data-Stats”
US Bureau of Labor Statistics
US Census Bureau Data
US Energy Information Administration
US Government Web Services and XML Data Sources
USA Facts
USENET corpus (2005-2011)
Utah Open Data
Varieties of Democracy.
Western Pennsylvania Regional Data Center
WHO Data Repository
Wikipedia List of Datasets for Machine Learning
WordNet
World Values Survey
World Wealth & Income Database
World Wide Web: 3.5 billion web pages and their relations
Yahoo Data for Researchers
YouTube Network 2007-2008