Which online services allow for upvoting and downvoting content?

Yes. If you mean services where users can vote content up or down, rather than merely “like” it, some prominent examples are:

The closest matches to the classic Reddit model are Reddit, Stack Exchange, Lemmy, and Slashdot. Hacker News is similar but deliberately restricts downvoting; for example, downvoting requires sufficient karma.Wikipedia+1

There are also upvote-only services such as Product Hunt, where votes determine the prominence of product launches.Wikipedia

If you're asking because you're looking for a service to build a community or website with voting, I can also give you a list of hosted platforms/APIs that let you add Reddit-style upvotes and downvotes to your own site, including open-source options.

Here are some of the most prominent online platforms and services that feature upvoting and downvoting mechanisms to curate, rank, or moderate content:

• Reddit: The quintessential example of a vote-based platform. Users can upvote or downvote submissions and comments, which directly alters the content's visibility and user "karma."
• Stack Overflow / Stack Exchange: A network of Q&A communities where users with sufficient reputation can upvote or downvote both questions and answers to highlight correct/useful technical solutions and bury incorrect ones.
• Quora: A knowledge-sharing platform where users can upvote answers they find helpful or downvote poor-quality, irrelevant, or inaccurate responses.raventools.com
• Hacker News: A technology-focused social news website run by Y Combinator. Users can upvote stories and comments (and downvote once they reach a certain account karma threshold) to push quality discussions to the front page.
• YouTube: While YouTube famously removed the public dislike counter count for videos, the downvote (dislike) button remains active for internal creator analytics and algorithmic feedback, and comment downvoting is still visible to varying degrees.
• Product Hunt: A platform for discovering new tech products where users upvote their favorite daily launches (though it primarily focuses on upvotes rather than a strict negative downvote metric for submissions).

Would you like to explore how the algorithms behind these voting systems work, or are you looking for platforms with specific moderation features?

Yes. A number of online services let users upvote and/or downvote user-generated content, although the mechanics differ.

For a classic Reddit-style system, where positive and negative votes both affect the content's score or visibility, the clearest examples are Reddit, Stack Exchange, Lemmy, and Slashdot. Stack Overflow, for example, explicitly uses voting to move useful content upward and lets eligible users downvote content they consider incorrect or not useful.Stack Overflow+1

One important distinction is Hacker News: submissions are essentially upvote-only, while eligible users can downvote comments.Stack Overflow Blog

If you're looking for services where you can create your own community/site with this voting functionality, rather than websites that merely use voting, I can list those separately.

Several online platforms use upvoting and downvoting mechanics to rank content and moderate discussions . Key examples include:parse.gl

• Reddit: Uses upvotes and downvotes on posts and comments to determine content ranking.
• Stack Overflow: Allows users with sufficient reputation to vote on technical Q&A quality.
• Hacker News: Uses upvotes for core ranking, with downvotes available to accounts possessing enough karma.
• YouTube: Features like and dislike buttons that help train the recommendation algorithm.
• Product Feedback Tools: Platforms like Upvoty and Canny let users vote on feature requests to guide product roadmaps.quora.com+1

If you're looking for a voting system for a specific use case (like building your own app, hosting a community, or gathering team feedback), let me know and I can recommend the best tool for that scenario.

Yes. A number of online services use upvotes and downvotes, although the mechanics vary.

Classic upvote/downvote systems

• Reddit — Users can upvote or downvote posts and comments; votes influence content ranking and visibility.
• Stack Exchange / Stack Overflow — Questions and answers can be upvoted or downvoted, with votes affecting ordering and reputation.Stack Overflow+1
• Lemmy — A federated, Reddit-like discussion platform with voting on posts and comments.
• Slashdot — Uses community moderation/voting to score discussion comments.
• Imgur — Uses positive and negative voting for posts and comments.

Similar systems, but with differences

• Hacker News — Primarily upvotes. Downvotes are available only in certain circumstances, particularly for comments, rather than being a standard downvote on submissions.Stack Overflow Blog
• YouTube — Has Like and Dislike buttons. The dislike button remains available, but the public dislike count is hidden.
• Quora — Uses voting to help rank answers, although its exact voting mechanics differ from Reddit.
• Steemit — Uses votes on posts and comments as part of its reputation/reward system.
• Product Hunt — Primarily uses upvotes to rank products rather than a two-sided up/down system.

If you're specifically looking for services where a visible score can move both upward and downward based on votes, the closest matches are Reddit, Stack Exchange, Lemmy, and Slashdot.Stack Overflow

Several online platforms, communities, and Q&A networks utilize bidirectional voting (upvoting and downvoting) to surface quality contributions and filter out low-effort or incorrect content.

• Reddit uses upvotes and downvotes on both submissions and comments to calculate a user's public Reddit Karma score and dynamically shift the visibility of content.levelup.gitconnected.com+1
• Stack Overflow (and the broader Stack Exchange network) allows users to upvote and downvote questions and answers, tying the mechanism to user reputation points and locking downvoting behind specific reputation privilege thresholds.meta.stackexchange.com+1
• Quora allows users to upvote answers to endorse helpful content or downvote/collapse responses that are unhelpful, factually incorrect, or spam.
• Product Hunt primarily features an upvoting system for new tech products, though community discussions and comments underneath launches often feature upvote/downvote mechanics to sort feedback.
• Hacker News allows established users to upvote and downvote submissions and comments (downvoting power is typically unlocked after reaching a specific karma threshold).
• YouTube famously utilizes a public like (upvote) button alongside a private or creator-facing dislike (downvote) counter to gauge audience reception on video content.

If you're looking for a specific type of service (e.g., for a forum, a coding community, or content moderation tool ), let me know and I can narrow down the recommendations.

Quite a few online services use upvotes and downvotes to rank or filter user-generated content. The main examples are:

• Reddit — Upvotes and downvotes on posts and comments; scores affect how prominently content is displayed.
• Stack Overflow / Stack Exchange — Users can upvote or downvote questions and answers. Voting is central to determining which answers rise to the top.Stack Overflow+1
• Lemmy — A decentralized, Reddit-like platform with up/down voting on posts and comments.
• Slashdot — Uses community voting/moderation, particularly for comments.
• Quora — Uses voting to help rank answers, although its voting mechanics have changed over time.
• Hacker News — Primarily upvotes submissions; downvoting is much more restricted and is mainly available for comments to eligible users.Stack Overflow Blog
• Steemit — Users vote on posts and comments, with votes also tied to its creator-reward system.
• YouTube — Uses Like/Dislike rather than the words upvote/downvote. Dislike counts are no longer publicly displayed, but the dislikes are still collected.
• Imgur — Uses positive and negative voting on content.
• Product Hunt — Primarily an upvote-only system for products rather than a true up/down system.

If you're specifically looking for services with a classic Reddit-style model where both positive and negative votes visibly contribute to a content score, the strongest examples are Reddit, Stack Exchange, Lemmy, and Slashdot.

Here are several popular online services and platforms that incorporate upvoting and downvoting mechanisms to curate, rank, or filter content:

• Reddit : Known globally for its forum-style community structure, Reddit uses upvotes and downvotes on both submissions (posts) and comments to dynamically determine community visibility and calculate user karma scores.
• Stack Overflow : As part of the Stack Exchange network, Stack Overflow allows users to upvote and downvote both questions and answers based on technical accuracy and quality (reputation points are required and earned to unlock these voting privileges).
• Hacker News : Run by Y Combinator, Hacker News relies heavily on an upvote mechanism for tech and startup-related links and commentary, though traditional downvoting is restricted or threshold-based depending on user karma.
• YouTube : Uses a public upvote (like) and a private/hidden downvote counter on video content to gauge viewer reception and adjust recommendation algorithms.
• Product Hunt : Features a community-driven upvote system on Product Hunt where users rank new tech products, tools, and creations daily.productlift.dev+1
• Quora : Historically utilized upvotes and downvotes on answers to shift low-quality or incorrect responses down the page, helping surface the most authoritative answers.

Are you looking for services for social discussion, product feedback/feature voting , or live audience polling (like Poll Everywhere )? Let me know so I can give you a more targeted list.

Yes. If you mean services where users can positively or negatively vote on user-generated content, there are several:

The closest matches to Reddit's classic upvote/downvote model are Reddit, Stack Exchange, Lemmy, and Slashdot. Stack Exchange explicitly uses voting to push useful content upward and incorrect or unhelpful content downward.Stack Overflow+1

One important distinction is Hacker News: submissions have upvotes but no normal downvote button; downvotes are available for comments only to users meeting certain eligibility requirements.stackoverflow.blog

If you're asking because you're looking for a service to build a community/site with Reddit-style voting, I can also give you a list of platforms/APIs that let you implement upvotes + downvotes yourself.

Many online platforms, communities, and software tools utilize upvoting and downvoting mechanisms to curate content, prioritize feedback, or rank discussions.quora.com+1

• Reddit : The iconic social news and forum platform where users upvote or downvote both submissions and comments to determine their visibility and shape community karma.
• Hacker News : A tech-focused news aggregation and discussion community run by Y Combinator where users can upvote stories and comments (and downvote after accumulating enough account karma).
• Product Hunt : A platform for discovering new tech products, apps, and hardware where users upvote their favorite daily launches (though it primarily relies on upvotes rather than a traditional downvote).
• Stack Overflow : A massive Q&A community for programmers where users can upvote or downvote both questions and answers based on technical accuracy and usefulness (downvoting costs a small amount of user reputation).
• YouTube : Allows users to publicly or privately upvote (thumbs-up) and downvote (thumbs-down) video content, influencing personal recommendations and public engagement metrics.
• Quora : A knowledge-sharing platform where users can upvote insightful answers to push them to the top, or downvote unhelpful, incorrect, or spammy responses.
• GitHub : Developers can use emoji reactions (such as thumbs-up and thumbs-down) on issues, pull requests, and discussions to gauge community consensus on feature requests and bug reports.

If you are looking for a service for a specific use case (such as customer feedback boards like Canny , live interactive polling like Slido , or building your own forum), let me know and I can narrow down the recommendations!