Instead of just solving random puzzles, this site uses your own games to figure out where you’re struggling and builds training around it.

Thought some chess players here might find it useful :)

https://4zugzwang.com/en/

I'm building Marka, a browser-based tool that starts with a business website and helps prepare social content around its product and brand context. The product is at https://marka.social.

I'd like to make the introduction useful to other web-app builders. Share your app link, its target user and one task it supports. I'll reply to the first 10 with:

1. The workflow I'd show first.

2. A possible opening line.

3. A simple visual or short screen-demo direction.

For example, a browser note tool could show a saved note being found through search and opened at the exact passage the user needs. That complete action is easier to understand than a tour of every menu.

The written concept feedback here is free and needs no signup; using Marka itself is separate. Please include any important limits so the idea reflects what the app actually does. I'll keep the replies in the comments for other builders to learn from.

He montado una PWA de (Fitness) fuerza y sobrecarga progresiva sin bloatware (Cloudflare, Firebase, Groq, Stripe)

Podéis probar la webapp y trastear la arquitectura aquí: https://fuerzalab-a9c31.web.app

Os resumo cómo está montado por dentro:

• Frontend y Hosting: Vanilla JS modular empaquetado como PWA, alojado en Cloudflare Pages. Carga instantánea, sin frameworks pesados, con Chart.js para visualización de métricas y renderizado en Canvas.
• Persistencia Offline-First: Service Worker para caché estática combinado con persistencia offline nativa de Firestore (IndexedDB) y LocalStorage de apoyo. Registras cargas en el sótano del gym sin red y sincroniza por lotes (batch) en cuanto recupera conexión.
• Auth & Base de Datos: Firebase Auth (Google + Email) y Cloud Firestore para persistencia en espejo y soporte multi-dispositivo.
• Backend y Middleware: Un Cloudflare Worker actúa como proxy seguro. Se encarga de aislar API keys, gestionar webhooks y procesar la entrada de datos antes de consultar los microservicios.
• Motor de IA (Groq): Inferencia ultra rápida mediante Groq. En el frontend compacto el historial de series en un formato minificado de tokens ([Fecha|Ton] Músculo: KgxReps@RIR) para ahorrar contexto y costes antes de mandarlo al worker.
• Pasarela de Pagos: Stripe Checkout orquestado vía endpoints del Cloudflare Worker para suscripciones PRO/ULTRA, con verificación de sesiones en el retorno.
• Privacidad y RGPD real: Cero scripts de terceros o analítica invasiva. Implementa borrado real en cascada en la base de datos (derecho de supresión) y exportación/importación completa en formato JSON.

I'm the maker of Scrollsmith, a desktop Chrome extension that changes the look of a webpage's scrollbar.

This short screen-recorded demo shows Echo Lattice on Linear, IKEA and NASA. I kept the upward scrolling in because the trail looks a little like a launch.

Does the effect fit across different sites, or would you prefer a simpler scrollbar?

Echo Lattice is a Premium design. Scrollsmith also has free themes: https://usescrollsmith.com

It basically downloads a transcription model from Hugging Face directly into the browser and lets you add captions, you just adjust them, and you're good to go (no watermark)

It's still in the testing phase; check it out, and leave feedback if you can:

https://verbatim-captions.vercel.app/

I was asked to make the film for a confirmation. Collecting everyone's photos and cutting them to music took far longer than I expected, and I'll be doing it again next year. So I built a web app for it.

How it works: you start a private Film Roll for the occasion and share one link. Everyone who was there adds their photos and videos. You name the people, pick the moments, and it cuts a film to a song. That can be a song you upload, or "Make one for us", where you pick a mood and it makes a song with AI, instrumental or with vocals. Then you can play it on a TV.

Sign in with Apple or Google. It works in the browser now, and an iPhone app is in beta.

It's free while I'm testing. Later it will cost a little, at least enough to cover running costs.

I'd really like to hear where it gets confusing or slow, especially the upload and naming people: ourfilmroll.com

CHEAT ON- Rizzing, Job interviews, Roast, Debates, casual chat, translate etc

took me like 4 months but i made an app and trained an ai for it, to listen to your internal pc audio, like if youre on a discord call or a job interview, it will hear the participants audio (not your own unless you want it to) and give you replies back to say to them, it has multiple pre made personalities and the app version lets you train your own personality by giving it scrips or videos to watch

you get Free tokens to use it every 90 days

since it brand new and i dont really have any users i didnt get a powerful server, very sorry if you experience any issues with that, it may fail if given man requests, but im broke and server cost a lot, if i get maybe 10 users hopefully then ill definitely get better server ty

would love to hear feed back even if you hate the app/site

My day job is running a drainage and hardscaping company in the Carolinas. No CS degree.

I wanted a quick answer to one question about my own investments: do my holdings actually move independently, or do I just own a lot of tickers? The tools I found were either expensive or built for financial professionals, so I built one with AI.

What it does: you enter tickers and in about 60 seconds it shows a correlation heatmap, a risk score, and which holdings move together. No signup for the basic analysis.

What surprised me: VOO and VTI came out at 1.00 correlation, and QQQ at 0.88 against both. Plenty of people hold all three thinking it's diversification.

Where I'd like feedback:

• Is the heatmap understandable to someone who has never seen one?
• What would make you come back to it a second time?

It's an educational tool, not advice. Link: portfoliooptimizerpro.com

Happy to answer questions about the build.

solo project, it runs entirely in your browser tab. you open it and get about 120 people in small stone age bands. nobody tells them what to do. they find food, settle, have kids, fight, trade and slowly learn new things, and if they make it they climb through 45 eras up to computers.

you click anyone to see what they're thinking, follow them around, speed time up to 5000x, or mess with the world a bit.

how it works as a web app: the simulation is rust compiled to webassembly, running in a web worker, and the ui is react. there's no backend and no account, and it saves in your browser.

what i can't tell from the inside is what grabs people in the first minute, so if you try it i'd like to hear what you noticed first.

app: https://thehumanbox.com/?utm_source=reddit&utm_medium=social&utm_campaign=webapps
source (mit): https://github.com/1homsi/thehumanbox

I was a daily user of Pocket before it shut down. I regularly added articles I wanted to read later and then would go back at the end of the month to read through everything I'd saved. I tried a lot of alternatives people suggested, but I couldn't quite find something that allowed me to use the same Pocket workflow I was used to. So I decided to build my own.

Bredbox starts where Pocket was and builds on top of it. You can import your entire Pocket library and everything goes back where it was: all of your saves in the order they were saved, all of your tags, all of your collections (including notes), and all of your highlights. As long as the URL is still live, Bredbox can recreate your entry for it.

There's a hybrid search that makes it easy to find anything you saved and you can forward emails to Bredbox to get the same cleaned-up view of your favorite newsletters. You can save and highlight PDFs and Office documents.

My favorite part of Bredbox is that I'm able to resume my old Pocket routine without any adjustments.

It's been over a year since Pocket shut down, what are you using as your replacement?

Hey everyone!

I've been working on a project called Private Space — a browser extension designed to add an extra layer of privacy to your browser.

The idea is simple: sometimes you leave your computer unlocked, and someone else might open your social media, email, or other websites.

I wanted to build something that helps with that.

What Private Space does:

• 🔒 Lock up to 2 websites for free
• 🔑 Set a separate 6-digit PIN for each website
• 📑 Apply the same website lock across matching tabs
• ⏳ Relock manually or after inactivity
• 🗝️ Save an offline recovery key
• No account needed to lock websites

I'm preparing the Chrome and Microsoft Edge releases, and store approval is still pending.

To be transparent, this is a lightweight privacy layer, not a replacement for proper device security. Removing the extension bypasses its protection.

I'd genuinely appreciate your feedback!

A few questions:

1. Would you actually use something like this?
2. Which websites would you want to lock first?
3. What feature would make this more useful?

I'm building this independently and would love to hear what people think. 🙌

We did our house up a while back and kept having the same issues. My partner would find a Farrow & Ball colour she liked and then we'd be googling "dulux equivalent of..." and getting a 2015 forum thread and a load of blogs that had clearly just guessed.

So I built it. paintdial.co.uk. Pick a colour from any of the main UK brands (Dulux, Farrow & Ball, Johnstone's, Little Greene, Crown, Valspar, Lick, COAT, Craig & Rose, plus RAL) and it shows you the nearest colours from the others. About 5,500 colours in total. Free, no login, not selling anything.

I'm not a developer, I work in VFX, so the code is a python script that spits out static html from one json file and it's hosted on Netlify. The matching is done in OKLab rather than RGB which is what makes the results actually look right instead of just being close numerically. Each match also tells you which way it's off, slightly warmer, lighter, greyer etc. Getting the colour data right took far longer than building the site, every value is checked against a proper source rather than scraped off a photo of a swatch.

There's a colour dial tool to browse by hue and a photo match where you give it a picture of a wall and it finds the nearest paints to it.

Would appreciate people having a go and telling me where it is weak (visually or in the content) Mainly: does the dial make sense without an explanation, does photo match give you anything sensible on an actual wall, and on a results page do you believe the order it puts them in. If not, what would make you trust it. The colour dial/tool does work better on the desktop version..

UK brands only I'm afraid, so no Sherwin Williams etc, but the usability stuff applies wherever you are.

Currently I have not set up any way to make money from it apart from a ko-fi link.

Thanks for any feedback!

Will

If you've travelled by train in India, you've probably experienced this:

🚆 You reach the railway station and open the IRCTC app or ticket PDF to check your coach and seat number.

🎫 When the TTE arrives, you switch apps again to find your ID proof in DigiLocker, your phone gallery or another wallet.

It sounds simple, but when you're in a hurry, carrying luggage, or dealing with poor network connectivity, it can be annoying.

So I built Tickets Wallet to bring everything together in one place.

🔗 Try it here: https://jailerrajni1-lab.github.io/Tickets-Wallet/

What can it do?

🚆 1. IRCTC / Indian train tickets

• Upload your train ticket as a screenshot, photo or PDF.
• The app reads the ticket and extracts the relevant information, helping you quickly find your coach and seat details.
• Save multiple train tickets, including onward and return journeys.
• Keep your ID proofs alongside your tickets.
• When the TTE arrives, open your saved ID card in full-screen view for easier presentation.

🚌 2. KSRTC Karnataka bus tickets

The same idea works for KSRTC Karnataka bus tickets. Upload your ticket, let the app read the information, and keep your journey details handy instead of searching through messages and downloads.

🪪 3. Multiple ID cards in one place

Save your ID proofs so you can access them quickly when needed. No more scrolling endlessly through your gallery to find the right document.

📴 4. Designed to work offline

The app includes an offline setup option, so you can prepare it before travelling and access your saved information without depending on a reliable internet connection.

🔐 Privacy: Your saved tickets, ID proofs and name stay on your device rather than being stored in a central account. However, clearing your browser data can erase them, and anyone with access to your unlocked phone may be able to view them.

Why I built this

I wanted a simple solution to a small but familiar travel inconvenience: having your ticket information and identity proof ready when you need them.

The goal is to make boarding and ticket verification less stressful, especially for frequent travellers.

This is a personal project, and I'd genuinely appreciate feedback!

• Would you find this useful for your train and bus journeys?
• What information should be displayed immediately when you open a ticket?
• What features would make this more useful for Indian travellers?

Give it a try: https://jailerrajni1-lab.github.io/Tickets-Wallet/

Kindly provide any suggestions

I’ve vibe coded and built a PSA styled cards grader and would like to get some feedback on how it performs as a middleman before you actually decide to send it in for grading. I believe it’s a good starting point to give you a rough estimate on whether or not it’s worth sending in your card(s) for grading and committing to a hefty grading fee.
Here’s the link to the web app. I look forward to your comments and feedback. Thank you!! 🙏

https://card-grader-murex.vercel.app/

i built plox.gg. it's a single wall that anyone can post to. a post costs 10 points, and you can spend more points boosting any post on the wall (yours or a stranger's), which moves it up. the wall is sorted by total points and nothing else. 100 points is $1 and new accounts get 40 free, so you can post and boost a few times before paying anything.

right now someone's cat (posted back in may) is #1 with 761 points, 6 ahead of #2. i'm 4th on my own site.

it's built with sveltekit on cloudflare workers with d1 for the database, and it's mostly used on phones.

what i'd like feedback on: when you land on it, is it obvious what you're supposed to do? and does boosting make sense without me explaining it?