Developed by Canadian programmer Christian Selig, a former Apple intern, Apollo was designed as an iOS-friendly successor to Alien Blue, and an alternative to the official Reddit app.

Throughout its lifespan, it received critical praise and became one of the most popular third-party Reddit clients, with close to 5 million lifetime global installs by 2023.

In April 2016, Alien Blue was discontinued and removed from the App Store in favour of a new, rewritten Reddit application.

[5] After being tested in public beta since early 2015,[6] Apollo officially launched on the App Store for iOS on 23 October 2017.

[7] Halifax-based[8][9] developer Christian Selig, a former Apple intern,[10][11] said in his Reddit introduction post that he saw the app as a suitable replacement for Alien Blue, and that the new official app, unlike Apollo, had not incorporated fan-favourite features from the "incredible" Alien Blue, such as inline previews for external media links.

[13] Beginning in 2018, Selig ran an annual[14] fundraiser on his birthday for the Nova Scotia Society for the Prevention of Cruelty, donating Apollo's proceeds for a day each year.

[17] On 18 April 2023, Reddit announced it would begin to charge for access to its application programming interface (API), citing data scraping by LLMs as its primary reason.

[27] The new terms came following similar changes by Twitter and preceded a rumoured initial public offering by Reddit.

[35] Premium tier subscribers received an automatic pro-rated refund for time remaining on their subscription, which they had the option to decline.

[23] Apollo was created to better follow established iOS human interface guidelines than competing Reddit clients.

[25] The app's global navigation bar featured five main tabs: Posts, Inbox, Account, Search, and Settings.

[7][38] An optional "Pro" tier was available as an in-app purchase and unlocked features geared towards power users such as post creation, multiple account support, and GIF scrubbing.

[45] In September 2022, Selig added a feature to Apollo called "Pixel Pals", a Tamagotchi-like virtual pet that would sit on top of the Dynamic Island as the user browsed Reddit.

[48] It was later spun off into its own app,[25] which received a major 2.0 update in September 2023 that introduced additional game elements.

[32][48] An update following Apollo's shutdown added the ability to transfer characters to the standalone app.