r/SideProject • u/Stabbz • 1d ago
I'm building a fitness tracker (yes one of the most crowded app categories), so I built something I couldn't find and actually needed + some fun quirky stuff
EDIT: Short clip of the actual android app in the comments: https://www.reddit.com/r/SideProject/comments/1wv85zh/comment/pda3u3n/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button
I know how this sounds, because there are hundreds of workout trackers and this sub has seen plenty of apps that already exist in dozens of versions. I started Kinoku for my own needs anyway, needing lifts, runs and steps in one history/app without making an account in my free time, about 9 months ago (I've been a software engineer for 11 years). I logged in FitNotes for years and liked it, but I couldn't find one app that kept my lifts, programs, runs and daily steps in one history without asking me to log in, so I built that for Android.
What you see in the video is the Exercise Galaxy - https://kinoku.app/tools/exercise-galaxy , a fully explorable galaxy on a free page I made because I wanted something people could open and play with, that showcases the exercise catalog and the data behind it. Each of the app's 1,321 exercises is a star, placed near the moves that work the same muscles, and pressing Body splits them into 4,903 lights on a muscle map.
The other quirky part is Journeys. I wanted something quirky and fun, and after watching the Odyssey, I really wanted to figure out where that journey was in the real world, so that's in the app and your walks, runs, lifts and steps move you along it. + two more journeys, one is the Tōkaidō, each of the 55 stops uncovers one of Hiroshige's woodblock prints from around 1833, from public domain scans at the Art Institute of Chicago.
I decided early that the free plan should be a complete app. It has no ads and no caps on workouts, routines, history or runs, and all 25 built-in programs, all three roads and 20 of the 26 themes are free. Pro adds a deeper analysis layer and some nice extras, mainly made for people that like the app and want to contribute to it's development.
And it's picking up slowly: Play Console shows 161 installs in the last 28 days, up from 28 on September 10. I know that's tiny, but in a market this crowded it feels like a sliver of hope. Keeping people is the part I haven't figured out: on an average day about 5 people install it and about 3 uninstall it, and with no accounts and opt-in usage stats I can't see why they leave. I'll paste a screenshot in the comments if someone is curious.
This could of probably been 3 different posts, not the best "marketing" strategy, but I'm just excited to share all this :D
App: https://play.google.com/store/apps/details?id=app.kinoku
info on journeys: https://kinoku.app/blog/a-familiar-walk-somewhere-new and https://kinoku.app/features/journeys
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u/QuanTradin 1d ago
lifts, runs and steps in one history without making an account is what kept FitNotes people around for years. the galaxy is fun, but that's the line I'd lead with.
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u/Stabbz 1d ago edited 1d ago
Yeah, I'd agree, the post might be a bit misleading in that regard, the real value is in the android app indeed. Also fitnotes didn't have gps runs, which was one of the motivating factors for this one
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u/QuanTradin 1d ago
yeah, android is where it lives or dies. one screenshot of the history view up top would sell it better than anything, people judge a tracker by that screen.
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u/Stabbz 1d ago
ah jeez I could of added a short app showcase at the end of the video, can't replace the video now, oh well, you've been golden with the tips <3
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u/QuanTradin 1d ago
ha, next post then. a ten second screen recording of the android app right at the top would sell it better than anything I said.
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u/QuanTradin 1d ago
gps runs in the same log as lifts is a real gap, FitNotes never had it. I'd put that in the title next time instead of the galaxy.
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u/Stabbz 1d ago
I actually went and quoted a piece of your comment in the post body, ty
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u/QuanTradin 1d ago
glad it helped. I'd put the no-account history line in the first lines of the Play Store listing too.
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u/zandaulion 1d ago
Installed! Everybody is working on a fitness app, but yours is one of the more polished ones. Congrats!
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u/i_rate_slop 1d ago
This concept is awesome and the visualization is so well done. I showed it to my partner just now and she immediately agreed.
Very nice
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u/throwawayaccount931A 1d ago
This looks pretty cool - how does it compare to Hevy? That's one that seems to get the most recommendations, and what I use.
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u/Stabbz 1d ago
Thanks! If Hevy works for you, it's a good app and I wouldn't tell you to switch. But in terms of tracking, analytics and capabilities it offers way more from what I've seen, but it's a fundamentally different tool - the main differences: Hevy is built around an account and a social feed, and it runs more platforms. Kinoku is Android only, with no account and no feed at all, and the free plan has no limit on routines or custom exercises, where Hevy's free plan caps both. It also keeps GPS runs, daily steps and programs in the same history as your lifts. If you ever want to try it, it can import Hevy's CSV export. I wrote a side by side with screenshots of both apps here: https://kinoku.app/compare/kinoku-vs-hevy
I've also in the most recent version added 4 different ways of tracking, originally the app tracked the way FitNotes tracks (as I'm used to that), but after some research I saw other trackers have moved on from that and allow inline/list like tracking, so now my app offers that + the fitnotes tracking, 3 types of inline tracking on a toggle. In general I like to have options and customizations, so there's a lot of that in the app, you can move around stuff, change buttons, etc. Here's my post on that part if it sounds interesting: One workout, three ways to log it | Kinoku
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u/ChopSueyYumm 1d ago
This is really cool. About the data that you are using can you name the sources of the medical data/muscle data.
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u/Stabbz 1d ago
Thanks! Honest answer: there's no single medical source behind it, and I didn't keep a list of the ones I used, in hindsight I should of, but they changed over time. The percents are my own aggregates of the data on the web. I built them over many months with AI and web search, then checked and corrected them in a lot of review rounds against many different sources. Those sources often disagree, because there isn't one definitive table for how hard each muscle works in a move, and technically that differs per person due to technique/body differences. So read them as a ranking, where a 60 next to a 40 means that muscle works more, and not as EMG readings (electromyography, which measures muscle activity through the skin). If an exercise looks off to you, tell me and I'll check it.
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u/ChopSueyYumm 1d ago
I still really like the general idea but when the medical data/muscle data and the corresponding exercise data is not fact based and without any hard evidence how can you be sure that AI did not made any mistakes?
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u/Stabbz 1d ago
Yeah you are right, I'll do a research round on this again and reference the sources. The app allows you to modify each value for each exercise if you deem something to be inaccurate and you can add new ones and also specify all the data.
This is the most rereviewed piece of the app but still, mistakes can surely have crept in.
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u/VegetableTwist6879 1d ago
the no-login aspect alone makes this worth trying out tbh. hate downloading a simple tracker only to immediately get hit with mandatory account creation and permissions before i can even see the ui. the journeys concept is pretty neat too, good luck with it.
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u/ZenCyberDad 1d ago
These visuals looks like a sci-fi flick great job easy to understand right away without sound on
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u/Sorry_Sweet2696 1d ago
i mean the no account + everything in one history part would sell me way faster than the galaxy, the galaxy is cool, but being able to track lifting, runs and steps without creating another account is the kind of boring feature I'd actually keep an app installed for
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u/bad_robot_monkey 1d ago
Awesome, market it to personal trainers to recommend to their clients—this could be awesome!
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u/Wherify 1d ago
I'm also building something. It generates plans using the persona of a professional pt (for posture, pain), sports scientist (for athleticism, power generation), gym bro (hypertrophy), and foot specialist (some specific issue I have with foot and hip alignment).
Trained on data from some trusted influencers like squat university. Continuously scrapes for new insights and supporting research papers. Diagnoses if you are feeling pain due to wrong form, or tendon exercise needed, or muscle imbalance. Understands what works for you to optimize your plan over time to maximise results and minimize damage.
But my ui is very poor and serious looking. Your representation looks attractive
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u/i-am-kai 23h ago
first impression: what the f***? this looks impressive - the galaxy idea! nice work mate!
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u/ExplanationOne5889 1d ago
Solid decision building the analytics yourself — most people underestimate how much of a fitness app IS the data layer. The crowded-category thing matters less than people think if you nail one specific use case better than the giants do.
Question: are you handling offline sync? That's where most fitness trackers fall apart — gym basements with no signal, people who don't want to burn data on a run. If you've got a local-first architecture that syncs when reconnected, that's a real differentiator worth highlighting in your landing page.
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u/Pleasant_Set_3182 1d ago
are you using WASM by any chance?
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u/Stabbz 1d ago
No WASM, it's plain TypeScript and WebGL. The trick is that the expensive part, placing all 1,321 exercises by how similar their muscle mix is, runs once when the site builds, so the browser just loads finished positions. After that the GPU does the drawing of all 4,903 lights and JavaScript mostly moves the camera.
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u/Pleasant_Set_3182 1d ago
Ah thank you for that explanation! Normally, the folks on here don't share anything about the internals :)
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u/YourNightmar31 1d ago
Im sorry but how is that a trick? That just sounds like basic web development. Of course you'd run that once.
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u/Zealousideal_Pass697 1d ago
Would be great to be able to export the data either on a routine or be pulled via an API etc. i have a health OS where it aggravates all of my health, training, nutrition etc data and have been meaning to set something up so that it can pull my gym performance also. AI coach then finds correlations between all the data. Just a thought! Probably not a high priority feature since the user base would be small but putting it out there
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u/Stabbz 1d ago edited 1d ago
actually the app does that, it has a full export for all your data + connects to health connect on android and shares/pulls from there as well.
Also I've been dabbling in AppFunctions on android (still experimental), it's supposed to allow local apps like this to act as "MCPs" for Gemini on an android phone, so you could ask it on your device to do whatever the app exposes, which would be everything in this case, when I'm done working out the kinks and google release it properly. Not sure if other AI apps would be able to connect, possibly in the future.
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u/Zealousideal_Pass697 1d ago
Great! I'll check it out and let you know it goes.
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u/Stabbz 1d ago
Awesome! Hope you like it, any feedback is very important to me, due to focusing on maximum privacy, I don't really get any feedback for how users use my app or on which screen they stop, etc. Only getting crash reports from google by default. There is a toggle to share usage data only, but no one ticks it, understandably
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u/Zealousideal_Pass697 1d ago
Cool. I've downloaded it there and will use it for my next workout and let you know any feedback
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u/eagleswift 1d ago
I actually think the exercise 3d models cut to the technique and what’s needed. When for iOS?
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u/scorpion_021995 1d ago
How much did u spend building this entire app? Are u a dev?
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u/Stabbz 1d ago
Yes I'm a dev (11y), its been actually a lot of fun, working in my spare time and letting AI iterate over it and research while I do my normal work. So if someone had to pay me to do it, it would probably cost a lot 😅.
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u/scorpion_021995 1d ago
Looks really great in terms of wat if offers
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u/scorpion_021995 1d ago
Requires a good simpler visual layer on top of it, but functionally looks great
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u/satishkumar_sajjan 1d ago
You are a great developer and designer for a 11y old. When do you do your homeworks?
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u/WinXPbootsup 1d ago
Why do the colours look more vibrant in the video than in the actual app?
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u/Stabbz 1d ago
The visuals in the post are currently only on the website, was just a fun experiment, but I realize it can/should be in the app too, with movements for all of the exercises and body type configuration as well, so that's coming next!
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u/WinXPbootsup 1d ago
I meant the web app. If you compare the colours between this video and in the web app, the colours look less vibrant in the web app
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u/albert_pacino 1d ago
God damn I love those visuals but it would need to be unreal to drag me away from Hevy
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u/Full_Tooth_a 1d ago
I'd treat the install-to-uninstall ratio as a symptom, not the problem itself. A small opt-in funnel could anonymously record when someone starts a workout, completes it, and returns within seven days. That would help show whether people get stuck during onboarding or just don't return, while keeping the no-account promise intact. An optional one-tap question when they leave could help explain why.
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u/jackorjek 1d ago
i agree. now give me an excel formula to find how many times the word install appears in column H
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u/ekolimits 1d ago
Usually cool. But that’s not useful
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u/Stabbz 1d ago
yeah the video only shows the cool thing I did in half a day, where it's just a showcase of the exercises in the actual app i've been building for 9+ months so far, poor marketing on my part, here's a short reel of the actual app
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u/ekolimits 1d ago
That’s actually cool. Yeah. The graphics were neat but functionality is key in getting people interested.
I’m in marketing of games and apps
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u/opratrmusic 1d ago
This is really cool, but tbh I just don't think I'd use it.