It was founded by Claire Novorol, a British pediatrician, Martin Hirsch and Daniel Nathrath. Nathrath is a graduate of the University of Houston Law Center. Since its foundation in 2011, the company has raised $69.3 million.
The app started out as a platform service for doctors and was adapted in 2016 to focus on the bits patients could understand. The app takes reported symptoms, matches them with symptoms of patients of similar age and gender, and reports the statistical likelihood that the patient has a certain condition.
The Ada consumer product, the app, is currently available in English, German, Spanish, Portuguese, Swahili, Romanian, and French. As of September 2020, the Ada app has been downloaded 10 million times and completed 20 million symptom assessments. It is free of charge and has the highest consumer ranks among similar apps. Thanks to funding from the Bill & Melinda Gates Foundation and Fondation Botnar, in November 2019, Ada launched its app in both Swahili and Romanian.
Ada has been compared to WebMD, Babylon's GP at Hand app and Your.MD. In October 2017, when three apps were tested with symptoms from asthma, shingles, alcohol-related liver disease, and urinary tract infection, Ada performed very well; it asked about the most important symptoms and provided the best diagnoses. It produced diagrams showing which of the symptoms for each disease were present and the strength of the link, and a diagram of the percentage of people likely to have that diagnosis.
In October 2019 a German IT security professional claimed that the Ada app was sending sensitive user-data (f.e. symptoms, IPs, Android ad IDs etc) to the Amplitude product analytics service (api.amplitude.com), and some German users' insurance provider to their Facebook Analytics account.  
In September 2020, Broadband Commission for Sustainable Development issued a report identifying Ada as of the AI solutions that have the "potential to address existing health inequalities and provide medical expertise to clinicians, health workers, and patients alike - all with the aim of improving the quality, access, and cost of healthcare delivery."
Ada & Rare diseases
A 2019 retrospective study evaluated Ada DX potential impact in accelerating rare disease diagnosis with the following results:
- Ada’s top suggestion matched the confirmed diagnosis in 89.25% of cases (83 of 93 cases).
- In more than 56% of cases, Ada provided correct disease suggestions earlier than the time of clinical diagnosis.
- More than 33% of patients could have been identified as having a rare disease in the first documented clinical visit.
In 2020, the World Economic Forum awarded Ada and other 99 candidates as its "Technology Pioneers." Since its global launch in 2016, Ada has won several awards, such as App Promotion Summit's Fastest Growing App, Proddys Award for best Health and Fitness Product, CogX: Good Health and Well-being Award, German Brand Award, and German Innovation Award.
- "Can you really trust the medical apps on your phone?". Wired. 1 October 2017. Retrieved 22 September 2018.
- "Ada: Gesundheits-App mit Facebook-Tracker". Kuketz. 19 September 2019. Retrieved 14 October 2019.
- "Massive Datenschutzmängel in der Gesundheits-App Ada". Kuketz. 10 October 2019. Retrieved 14 October 2019.