What the apps do
Audiots is an iOS app containing more than fifty soundmojis: emojis that carry audio, so a message arrives with a noise attached rather than a static picture. The idea began as a personal hobby, and the decision to publish came from the recognition that other people might enjoy it too.
Cardoji applied the same instinct to a different format, offering customisable digital greeting cards aimed at a young audience. Both products sit in the same territory, the small decorative layer of messaging that teenagers use constantly and that adult software companies had largely ignored.
Brands, and a cat
The partnerships are the part that separates this from a school project. Entrepreneur reported deals with General Electric, HINT water and the SPCA, the animal welfare organisation, for which dog and cat emojis were released to raise awareness.
Branded emoji sets were a real marketing channel in this period. A company that wants to reach teenagers cannot easily buy their attention through advertising, but it can supply something they will use on their own messages. That is why a thirteen-year-old's app could be commercially interesting to an industrial conglomerate: it had the audience, and the audience was distributing the brand itself.
Who helped build it
Entrepreneur is clear that the venture drew on family expertise. Henderson's mother works in product marketing at Salesforce, the enterprise software company. An uncle is a sound engineer at LucasArts and assisted with the sound mixing, which is the hardest part of a soundmoji to get right: a clip must be short, immediately recognisable and not unpleasant on repeat.
This is not a qualification on the achievement so much as a description of how any child's product reaches the App Store. Publishing software requires a developer account, legal agreements and payment processing that a minor cannot hold. What varies between such stories is how much of the creative work is the child's, and here the concept, the catalogue and the company were attributed to Henderson.
Running a company around a timetable
At the time of the profile the work in progress was integration: connecting Audiots to email and to Facebook, so the sound-enabled emojis would travel beyond one app. Entrepreneur notes this was being done alongside schoolwork.
The stated reward was not the money. “The most fun part for me is the emails I get from people telling me they like the app,” Henderson told the magazine. The company, 4 Girls Tech, was small, and so was the product; the constraint was the ordinary one of being thirteen with homework.
Where Mercer Henderson is now
The record on this page ends in August 2016. It does not report download figures, revenue or the value of the brand partnerships, and it does not say whether Audiots and Cardoji remained available afterwards.
Nor is a date of birth published, and the source used here does not state a gender, so this page does not assume one. What is documented is a specific and unusual thing: a thirteen-year-old in San Francisco who turned a private joke about noisy emojis into a shipped product with national brands attached to it.
| Person | Country | Milestone | Age / Stat |
|---|---|---|---|
| Rishi Shiv Prasanna | India | Winning the Pradhan Mantri Rashtriya Bal Puraskar in 2023 at eight, for… | Age 0 |
| Cannan Huey-You | United States | Presenting research on a Milky Way gas cloud at the American Astronomical… | Age 11 |
| Mercer Henderson | United States | Audiots, an iOS app of 50+ soundmojis | Age 13 |
| Ángela Olazarán Laureano | Mexico | An AI medical assistant built in Veracruz, designed to work where there is | Age 14 |
| Émer Hickey | Ireland | Co-winning the 2014 Google Science Fair grand prize | Age 16 |
What is documented — and what is not
✓ Documented
- Aged 13 in San Francisco when profiled by Entrepreneur in August 2016
- Built Audiots, an iOS app of more than 50 soundmojis, plus the Cardoji greeting-card app (Entrepreneur)
- Partnerships with General Electric, HINT water and the SPCA; sound mixing help from an uncle at LucasArts (Entrepreneur)
? Unverified, disputed or wrong
- No date of birth published, and the source used here does not state a gender
- No download, revenue or partnership-value figures
- No information on the apps or on Henderson after August 2016
Questions people ask about Mercer Henderson
How old is Mercer Henderson?
Entrepreneur described Henderson as 13 in August 2016, placing the birth year around 2003. No date of birth is published.
What is Audiots?
An iOS app containing more than 50 soundmojis, emojis that play an audio clip rather than appearing as a static image.
What is Cardoji?
A second app offering customisable digital greeting cards aimed at a young audience.
Which brands worked with the apps?
Entrepreneur names General Electric, HINT water and the SPCA, with dog and cat emojis released in support of animal welfare.
Who helped make the apps?
Henderson's mother works in product marketing at Salesforce, and an uncle who is a sound engineer at LucasArts assisted with the sound mixing.
How many people downloaded Audiots?
No download or revenue figure appears in the source used here.
Is Mercer Henderson on Wikipedia?
No Wikipedia article was identified in the research behind this page.
Where is Mercer Henderson now?
Nothing after the August 2016 profile appears in the sources used here.
Quick quiz: how well do you know Mercer’s story?
What is a soundmoji, as Audiots uses the term?
Which organisation got dog and cat emojis for animal welfare?
Who helped with the sound mixing?
Sources
- 11 Successful Kid Entrepreneurs Keeping Their Eyes on the Prize — Entrepreneur, 2016-08-04
Checked by the Geniuses.club editorial team. Ages are given as of September 2026.
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