Which websites allow users to upvote or downvote content?

Yes. A number of websites let users upvote and/or downvote user-generated content. The mechanics differ somewhat:

• Depending on the site's configuration.

The most Reddit-like examples

If you're specifically interested in a visible positive/negative score that affects content ranking, the closest examples are:

• Reddit — votes affect how posts/comments are surfaced and contribute to karma.Reddit Help
• Stack Exchange — votes are central to ranking questions and answers, and also affect reputation.Stack Overflow+1
• Lemmy — decentralized, Reddit-style communities with voting on posts and comments.
• Slashdot — has a long-standing community moderation/scoring system.
• Hacker News — similar concept, but substantially more restrictive: stories are effectively upvote-only, while eligible users can downvote comments.techcrunch.com

If you're asking because you're designing a website with an upvote/downvote system, I can also compare these platforms' voting mechanics—e.g. whether votes are public, how scores are calculated, whether users can change votes, and how downvotes affect ranking.

Yes. A number of major websites let users vote positively or negatively on user-generated content. The mechanics vary, especially around whether downvotes are available to everyone.

Closest to a classic Reddit-style system

If you specifically mean a visible positive/negative vote that changes a content score and affects its ranking, the clearest examples are:

• Reddit — upvotes and downvotes directly influence the visibility/ranking of posts and comments.Reddit Help
• Stack Exchange — voting is central to ranking questions and answers, and votes also affect reputation.Stack Overflow+1
• Lemmy — closely follows the Reddit model with voting on posts and comments.
• Slashdot — has a long-standing community moderation/scoring system.
• Hacker News — similar concept, but substantially more restrictive: submissions are primarily upvote-based, while downvoting is limited by user privileges and applies differently to comments.Wikipedia

YouTube is worth separating from these: its Like/Dislike buttons function as positive/negative feedback, but YouTube no longer publicly displays the aggregate dislike count.

If you're researching this because you're building a website with an upvote/downvote system, I can also compare these platforms' voting mechanics—e.g. score calculation, karma/reputation, vote visibility, anti-abuse measures, and ranking algorithms.

• Reddit : A massive community-driven platform where users submit links, text, and images, then upvote or downvote submissions and comments to determine their visibility. Check it out on Reddit.
• Stack Overflow : A question-and-answer site for programmers where users can upvote and downvote both questions and answers to surface the most accurate technical solutions. Visit the platform at Stack Overflow.
• Hacker News : A tech-focused news and discussion site run by Y Combinator where users upvote or downvote submissions (primarily links and text posts) to rank the front page. Explore it at Hacker News.
• YouTube : Allows users to upvote (thumbs up) or downvote (thumbs down) video content, directly influencing public metrics and recommendation algorithms. Watch and interact on YouTube.
• Product Hunt : A platform for discovering new products where users upvote their favorite launches to push them to the top of the daily leaderboard. Browse the latest tech on Product Hunt.
• Quora : While primarily known for upvoting answers, the platform allows users to upvote or downvote answers to reward helpful responses and hide low-quality content. Read discussions on Quora.

Would you like to know more about how these voting systems impact content visibility , or are you looking for a platform for a specific use case (like coding, news, or entertainment)?

Yes. Quite a few websites use upvotes/downvotes or similar voting systems to let users collectively rank content.

The closest matches to Reddit's classic model—where positive and negative votes directly affect the ranking of content—are Reddit, Stack Exchange, Lemmy, and Slashdot. Reddit explicitly says its votes determine what gets surfaced in communities and conversations.Reddit Help+1

Hacker News is a special case: stories themselves can be upvoted but not downvoted; eligible users can downvote comments.TechCrunch

Digg is also worth mentioning if you're interested in the history of social voting: its current revival uses “digg” votes plus a “bury” mechanism for unwanted content.The Verge

If you're asking because you're looking for websites to post something and get community upvotes/downvotes, I can also give you a list of 20+ active platforms categorized by tech, news, products, questions, entertainment, or general content.

• Reddit : A massive network of communities based on people's interests where users submit posts and comments, which others can then upvote or downvote to determine their visibility. Check it out on Reddit.
• Stack Overflow : A question-and-answer platform for programmers and developers where users can upvote and downvote both questions and answers to curate the best technical solutions. Explore the platform on Stack Overflow.
• Product Hunt : A website that lets users share and discover new products, tech, and apps, using an upvote system to rank the best daily submissions. Visit the site at Product Hunt.
• Hacker News : A social news website focusing on computer science, entrepreneurship, and technology run by Y Combinator, featuring an upvote (and downvote/flagging for high-karma users) system. View the discussions on Hacker News.
• YouTube : A video-sharing platform that allows viewers to like (upvote) or dislike (downvote) video content, influencing recommendation algorithms and public metrics. Watch videos on YouTube.
• Quora : A question-and-answer website where users can upvote answers they find helpful or insightful (and downvote unhelpful ones) to push quality responses to the top. Browse topics on Quora.

If you're looking for a specific type of platform (like gaming, news, coding, or e-commerce ), let me know and I can tailor this list to your exact use case.

Yes. Many community-driven websites use voting to rank or filter user-generated content.

Websites with upvotes and downvotes

• Reddit — Users can upvote or downvote posts and comments, and voting affects what gets surfaced within communities.Reddit Help
• Stack Overflow / Stack Exchange — Questions and answers can be upvoted or downvoted; votes directly affect ranking and reputation.Stack Overflow+1
• Lemmy — A federated, Reddit-like platform where communities use upvotes and downvotes on posts and comments.
• Slashdot — Community voting/moderation is used particularly for comments.
• Quora — Uses voting to help rank answers, although its system isn't identical to Reddit's.
• Rumble — Provides upvote/downvote-style feedback on content.

Similar systems

• Hacker News — Stories can be upvoted, but story downvotes aren't available; sufficiently experienced users can downvote comments.Wikipedia+1
• YouTube — Has Like/Dislike buttons rather than traditional up/down votes; the public dislike count is hidden.
• Product Hunt — Users upvote products to influence their rankings.
• GitHub — Uses reactions such as 👍 and ❤️ rather than traditional up/down voting.

If you're specifically looking for sites where both the positive and negative vote totals are visible and directly affect a piece of content's ranking, Reddit and Stack Exchange are probably the clearest examples.Stack Overflow+1

• Reddit - A massive network of communities based on people's interests where users submit links, text, and images, which can then be upvoted or downvoted to determine their visibility. Check it out on Reddit.
• Hacker News - A social news website focusing on computer science, entrepreneurship, and technology where users can upvote and downvote submissions and comments (though downvoting requires a certain amount of karma). Explore it on Hacker News.
• Stack Overflow - A question and answer site for professional and enthusiast programmers where users can upvote and downvote both questions and answers to surface the most helpful technical solutions. Visit the platform at Stack Overflow.
• YouTube - A video-sharing platform that allows viewers to upvote (thumbs up) or downvote (thumbs down) video content, directly influencing engagement metrics and public feedback. Watch and vote on YouTube.
• Product Hunt - A website that lets users share and upvote new products, tech gadgets, websites, and software applications daily to highlight the best new innovations. Discover new tools on Product Hunt.

Would you like to know more about how voting systems work on a specific one of these platforms, or are you looking for platforms tailored to a specific niche (like gaming, design, or news)?

Yes. Many websites use upvotes/downvotes—or equivalent positive/negative voting—to rank and filter user-generated content.

Clear upvote + downvote systems

• Reddit — Users can upvote or downvote posts and comments; votes affect how content is surfaced.Reddit Help
• Stack Overflow / Stack Exchange — Questions and answers can be upvoted or downvoted, affecting ranking and reputation.Stack Overflow+1
• Lemmy — Reddit-like communities with voting on posts and comments.
• Slashdot — Community voting/moderation is used particularly for comments.
• Quora — Uses voting to help rank answers, although its voting mechanics differ from Reddit's.

Similar systems, but with important differences

• Hacker News — Stories are upvoted; downvoting is much more restricted and primarily applies to comments for eligible users.TechCrunch
• YouTube — Uses Like/Dislike rather than "upvote/downvote." Dislike counts are no longer publicly displayed.
• Product Hunt — Primarily an upvote system for products rather than a true up/down system.
• Steemit — Uses votes on posts and comments, with voting also connected to its rewards system.

If by "upvote/downvote" you mean a site where both positive and negative votes are publicly visible and directly determine the ranking, the strongest examples are Reddit, Stack Exchange, Lemmy, and Slashdot.Reddit Help+1

If you're researching this for building a website with an upvote/downvote feature, I can also give you a much larger list—e.g. 30–50 sites, categorized by social media, Q&A, news, product discovery, forums, and developer communities.

Here are some of the most popular platforms and websites that let users upvote or downvote (or react with similar voting mechanisms) content:

• Reddit: The classic upvote/downvote forum model. Users vote on posts and comments, which directly affects their visibility and the user's "karma" score.
• Stack Overflow: A community-driven Q&A site for programmers where users can upvote or downvote both questions and answers to highlight accurate solutions and bury incorrect ones.
• Hacker News: A tech-focused news aggregation and discussion site run by Y Combinator that relies on upvoting (and flagging) submissions and comments.
• Product Hunt: A platform for discovering new tech products, where users upvote their favorite daily launches to push them to the top of the leaderboard.
• YouTube: Allows users to upvote (thumbs up) or downvote (thumbs down) video content, influencing public sentiment and recommendation algorithms (though public downvote counts are often hidden or managed via creator settings/extensions).
• Quora: Features an upvote and downvote system for answers to boost helpful responses and collapse unhelpful or low-quality ones.

Would you like to know more about how algorithms use these votes or are you looking for a platform tailored to a specific topic?