Tumblr (stylized as tumblr and pronounced "tumbler") is a microblogging and social networking website founded by David Karp in 2007 and currently owned by Automattic. The service allows users to post multimedia and other content to a short-form blog. Users can follow other users' blogs. Bloggers can also make their blogs private.^[4][5] For bloggers many of the website's features are accessed from a "dashboard" interface.

As of August 12, 2019, Tumblr hosts over 475 million blogs.^[6] As of January 2016, the website had over 500 million monthly visitors,^[3] which dropped to less than 400 million by August 2019.^[7]

Development of Tumblr began in 2006 during a two-week gap between contracts at David Karp's software consulting company, Davidville (housed at Karp's former internship with producer-incubator Fred Seibert's Frederator Studios, which was located a block from Tumblr's current headquarters).^[8][9] Karp had been interested in tumblelogs (short-form blogs) for some time and was waiting for one of the established blogging platforms to introduce their own tumblelogging platform. As no one had done so after a year of waiting, Karp and developer Marco Arment began working on their own tumblelogging platform.^[10][11] Tumblr was launched in February 2007,^[12][13] and within two weeks the service had gained 75,000 users.^[14] Arment left the company in September 2010 to focus on Instapaper.^[15]

In early June 2012, Tumblr featured its first major brand advertising campaign in conjunction with Adidas, who launched an official soccer Tumblr blog and bought placements on the user dashboard. This launch came only two months after Tumblr announced it would be moving towards paid advertising on its site.^[16]

On May 20, 2013, it was announced that Yahoo and Tumblr had reached an agreement for Yahoo! Inc. to acquire Tumblr for $1.1 billion in cash.^[17][18] Many of Tumblr's users were unhappy with the news, causing some to start a petition, achieving nearly 170,000 signatures.^[19] David Karp remained CEO and the deal was finalized on June 20, 2013.^[20][21] Advertising sales goals were not met and in 2016 Yahoo wrote down $712 million of Tumblr's value.^[22]

Verizon Communications acquired Yahoo in June 2017, and placed Yahoo and Tumblr under its Oath subsidiary.^{[23][1][24][25][26][27]}

Karp announced in November 2017 that he would be leaving Tumblr by the end of the year. Jeff D'Onofrio, Tumblr's President and COO, took over leading the company.^[28]

The site, along with the rest of the Oath division (renamed Verizon Media Group in 2019), continued to struggle under Verizon. In March 2019, SimilarWeb estimated Tumblr had lost 30% of its user traffic since December 2018, when the site had introduced a stricter content policy with heavier restrictions on adult content (which had been a notable draw to the service).^[29] In May 2019, it was reported that Verizon was considering selling the site due to its continued struggles since the purchase (as it had done with another Yahoo property, Flickr, via its sale to SmugMug). Following this news, Pornhub's vice president publicly expressed interest in purchasing Tumblr, with a promise to reinstate the previous adult content policies.^[30][31]

On August 12, 2019, Verizon Media announced that it would sell Tumblr to Automattic—operator of blog service WordPress.com and corporate backer of the open source blog software of the same name—for an undisclosed amount. Axios reported that the sale price was less than $3 million, a significant decrease over Yahoo's original purchase price. Automattic CEO Matt Mullenweg stated that the site will operate as a complementary service to WordPress.com, and that there were no plans to reverse the content policy decision made by Verizon.^[32]

With Tumblr's 2009 acquisition of Tumblerette, an iOS application created by Jeff Rock and Garrett Ross, the service launched its official iPhone app.^[35][36] The site became available to BlackBerry smartphones on April 17, 2010, via a Mobelux application in BlackBerry World. In June 2012, Tumblr released a new version of its iOS app, Tumblr 3.0, allowing support for Spotify, hi-res images and offline access.^[37] An app for Android is also available.^[38] A Windows Phone app was released on April 23, 2013.^[39] An app for Google Glass was released on May 16, 2013.^[40]

Tumblr blogs may optionally allow users to submit questions, either as themselves or anonymously, to the blog for a response. Tumblr also offered a "fan mail" function, allowing users to send messages to blogs that they follow.^[41][42]

On November 10, 2015, Tumblr introduced an integrated instant messaging function, allowing users to chat between other Tumblr users. The feature was rolled out in a "viral" manner; it was initially made available to a group of 1500 users, and other users could receive access to the messaging system if they were sent a message by any user that had received access to the system itself. The messaging platform replaces the fan mail system, which was deprecated.^[43] The ability to send posts to others via the Dashboard was added the following month.^[44]

In May 2012, Tumblr launched Storyboard, a blog managed by an in-house editorial team which features stories and videos about noteworthy blogs and users on Tumblr.^[45] In April 2013, Storyboard was shut down.^[46]

In March 2018, Tumblr began to syndicate original video content from Verizon-owned video network go90, as part of an ongoing integration of Oath properties, and reported plans to wind down go90 in favor of using Oath properties to distribute its content instead. This made the respective content available internationally, since go90 is a U.S.-only service.^[47][48]

Tumblr has been noted for the socially progressive views of its users.^[49][50] In 2011, the service was most popular with the teen and college-aged user segments with half of Tumblr's visitor base being under the age of 25.^[51] In April 2013, the website received more than 13 billion global page views.^[52] User activity, measured by the number of blog posts each day, peaked at over 100 million in early 2014 and declined in each of the next three years, to approximately 30 million by October 2018.^[53]

As of May 2019, Tumblr hosts over 465 million blogs and more than 172 billion posts in total^[6] with over 21 million posts created on the site each day.^[1]

Tumblr has been noted by technology journalists as having a sizable amount of pornographic content.^[54][55] An analysis conducted by news and technology site TechCrunch on May 20, 2013, has shown that over 22% of all traffic in and out of Tumblr was classified as pornography. In addition, a reported 16.45% of blogs on Tumblr exclusively contained pornographic material. ^[56] Since July 2013 and its acquisition by Yahoo, Tumblr has progressively restricted adult content on the site. In July 2013, Tumblr began to filter content from adult-tagged blogs from appearing in search results and tag displays unless the user is logged in. In February 2018, Safe Mode (which filters "sensitive" content and blogs) became enabled by default for all users on an opt-out basis.^[57]

On December 3, 2018, Tumblr announced that effective December 17, all images and videos depicting sex acts, and real-life images and videos depicting human genitalia or "female-presenting" nipples, would be banned from the service. Exceptions are provided for illustrations or art that depict nudity, nudity related to "political or newsworthy speech", and depictions of "female-presenting" nipples in relation to medical events such as childbirth, breastfeeding, mastectomy and gender reassignment surgery. The new rules do not apply to text content. All posts in violation of the new policy will be hidden from public view, and repeat offenders may be reprimanded.^[58][59] Shortly prior to the announcement, Tumblr's Android app was patched to remove the ability to disable Safe Mode.^[60]

The change has faced wide criticism among Tumblr's community; in particular, it has been argued that the service should have focused on other major issues (such as controlling hate speech or the number of porn-related spambots on the service), and that the service's adult community provided a platform for sex education, independent adult performers (especially those representing LGBT communities who feel that they are underrepresented by a heteronormative mainstream industry) seeking an outlet for their work, and those seeking a safe haven from "over-policed" platforms to share creative work with adult themes.^[61][62][63] Tumblr stated that it is using various algorithms to detect potential violations, in combination with manual reviews.^[60] Users quickly discovered a wide array of false positives.^[64][65][66] A large number of users scheduled protest actions on the 17th.^[67]

On the day the ban took effect, Tumblr issued a new post clarifying the new policy, showcasing examples of adult images still allowed on the service, and stating that it "fully recognized" its "special obligation" to serving its LGBT userbase, and that "LGBTQ+ conversations, exploration of sexuality and gender, efforts to document the lives and challenges of those in the sex worker industry, and posts with pictures, videos, and GIFs of gender-confirmation surgery are all examples of content that is not only permitted on Tumblr but actively encouraged."^[68]

Wired cited multiple potential factors in the ban, including that the presence of adult content made the service unappealing to potential advertisers, the Stop Enabling Sex Traffickers Act (a U.S. federal law which makes websites liable for knowingly assisting or facilitating illegal sex trafficking), as well as heavy restrictions on adult content imposed by Apple for software offered on the iOS App Store (which similarly prompted several Reddit clients to heavily frustrate the ability for users to access forums on the site that contain adult content).^[60]

Tumblr's headquarters is at 770 Broadway in New York City.^[6][69][70] The company also maintains a support office in Richmond, Virginia.^[71] As of June 1, 2017, Tumblr had 411 employees.^[2] The company's logo is set in Bookman Old Style with some modifications.^[72]

As of 2011 Tumblr had received about $125 million of funding from investors.^[73] The company has raised funding from Union Square Ventures, Spark Capital, Martín Varsavsky, John Borthwick (Betaworks), Fred Seibert, Krum Capital, and Sequoia Capital (among other investors).^[74][75][76]

In its first round of funding in October 2007, Tumblr raised $750,000 from Spark Capital and Union Square Ventures.^[77] In December 2008 the company raised $4.5 million in Series B funding^[78] and a further $5 million in April 2010.^[79] In December 2010 Tumblr raised $30 million in Series D funding.^[80] The company had a $800 million valuation in August 2011.^[81] In September 2011 the company raised $85 million in a round of funding led by Greylock Partners and Insight Venture Partners.^[82]

In an interview with Nicole Lapin of Bloomberg West on September 7, 2012, David Karp said the site was monetized by advertising. Their first advertising launch started in May 2012 after 16 experimental campaigns.^[83] Tumblr made $13 million in revenue in 2012 and hoped to make $100 million in 2013. Tumblr reportedly spent $25 million to fund operations in 2012.^[73]

In 2013, Tumblr began allowing companies to pay to promote their own posts to a larger audience. Tumblr Head of Sales, Lee Brown, has quoted the average ad purchase on Tumblr to be nearly six figures.^[84] Tumblr also allows premium theme templates to be sold for use by blogs.^[85]

In July 2016, advertisements were implemented by default across all blogs. Users may opt out, and the service stated that a revenue sharing program would be implemented at a later date.^[86]

Tumblr has received criticism for copyright violations by participating bloggers;^[87] however, Tumblr accepts Digital Millennium Copyright Act (DMCA) take-down notices.^[88] Tumblr's visual appeal has made it ideal for photoblogs that often include copyrighted works from others that are re-published without payment.^[89] Tumblr users can post unoriginal content by "Reblogging", a feature on Tumblr that allows users to re-post content taken from another blog onto their own blog with attribution.^[87][90]

Tumblr has been forced to manage spam and security problems. For example, a chain letter scam in May 2011 affected 130,000 users.^[91]

On December 3, 2012, Tumblr was attacked by a cross-site scripting worm deployed by the Internet troll group Gay Nigger Association of America. The message urged users to harm themselves and criticized blogging in general.^[92]

In 2015, Tumblr faced criticism by users for changes to its reblog mechanisms. In July 2015, the system was modified so that users cannot remove or edit individual comments by other users when reblogging a post; existing comments can only be removed all at once. Tumblr staff argued that the change was intended to combat "misattribution". In September 2015, Tumblr changed how threads of comments on reblogged posts are displayed; rather than a nested view with indentations for each post, all reblogs are now shown in a flat view, and user avatars were also added. The change was intended to improve the legibility of reblogs, especially on mobile platforms, and complements the inability to edit existing comments. Although some users had requested such a change to combat posts made illegible by extremely large numbers of comments on a reblogged post, the majority of users (even those who had requested such a change) criticized the new format. The Verge was also critical of the changes, noting that it was cleaner, but made the site lose its "nostalgic charm".^[93][94]

In February 2012, Tumblr banned blogs that promote or advocate suicide, self-harm and eating disorders (pro-ana).^[95]

The suicide of a British teenager, Tallulah Wilson, raised the issue of suicide and self-harm promotion on Tumblr as Wilson was reported to have maintained a self-harm blog on the site. A user on the site is reported to have sent Wilson an image of a noose accompanied by the message: "here is your new necklace, try it on." In response to the Wilson case, Maria Miller, the UK's minister for culture, media and sport, said that social media sites like Tumblr need to remove "toxic" self-harm content.^[96][97]

Searching terms like "depression", "anxiety", and "suicide" on Tumblr now brings up a PSA page directing the user to resources like the national suicide lifeline, and 7 Cups; as well as an option to continue to the search results.^[98]

There are concerns of some Tumblr posts glorifying suicide and depression among young people.^[99]

In February 2018, BuzzFeed published a report claiming that Tumblr was utilized as a distribution channel for Russian agents to influence American voting habits during the 2016 presidential election.^[100]

Despite policies forbidding hate speech, Tumblr has been noted for hosting content from nazis and white supremacists.^[101]

Several countries have blocked access to Tumblr because of pornography, religious extremism or LGBT content. These countries include China,^[102] Indonesia, Kazakhstan^[103] and Iran.^[104] In February 2016, the Indonesian government temporarily blocked access to Tumblr within the country because the site hosts pages that carried porn. The government shortly reversed its decision to block the site and said it had asked Tumblr to self-censor its pornographic content.^[105]

In November 2018, Tumblr's iOS app was pulled by Apple after illegal child pornography images were found on the service. Tumblr stated that all images uploaded to the service are scanned against an industry database, but that a "routine audit" had revealed images that had not yet been added to the database.^[106] In the wake of the incident, a number of Tumblr blogs—particularly those dealing primarily in adult-tagged artwork such as erotica, as well as art study and anatomy resources—were also deleted, with affected users taking to other platforms (such as Twitter) to warn others and complain about the deletions, as well as encourage users to back up their blog's contents.^[107][108] Tumblr subsequently removed the ability to disable "Safe Mode" from its Android app,^[60] and announced a wider ban on explicit images of sex acts and nudity on the platform with certain limited exceptions.^[58]

In August 2010, Tumblr was named as a finalist in Lead411's New York City Hot 125.^[109]

Celebrities who use Tumblr include Taylor Swift,^[110] Lady Gaga,^[111] Zooey Deschanel,^[111] John Mayer^[111] and Zayn.^[112]

On October 21, 2011, Tumblr became the first blogging platform to host Barack Obama's blog.^[113]