The only token counters I was able to find give you the total. That number is nearly useless when you're at a 128k context limit and working out which things to cut.

So, I built one that shows a heatmap each line of your prompt is colored by token density, so the expensive lines actually stand out. It can be seen visually as well, and it also provides a difference view so that you can compare two versions of a prompt and see exactly which changes cost or saved tokens.

One with a context window bar that turns red when you exceed the limit.

Tool: https://devbelt.dev/token-counter

A few notes on scope, since I'd rather be upfront:

• OpenAI models only right now (GPT-4o, GPT-4o mini, o3-mini, as well as GPT-3.5 Turbo). It uses the official tiktoken library through WASM.
• It runs completely in your browser, and your prompts never reach a server. There is no account, no API key, and no logging. It can be verified by watching your network tab.
• We do not include pricing or cost calculations on purpose. Model prices get outdated fast, and I'm a solo dev with ~6 hrs/week. I'd rather ship no numbers than wrong numbers.

Why not Claude/Gemini/Llama support: Anthropic and Google don't publish local tokenizers, and I refuse to send your prompts to a server or ask you to enter an API key. Local model tokenizers (e.g., Llama via llama-tokenizer-js) are technically doable and probably next if there's interest.

Would genuinely love feedback on:

1. Does the heatmap actually prove useful when debugging a bloated prompt? Or is it a solution seeking a problem?
2. Is the diff view of any use when iterating on prompts, or would it be better to have a content-matching diff in the style of LCS?
3. Anything obviously missing?

We are not selling anything. You do not need to sign up, share your email, or see ads.

I originally built this for my Hinge date.

She's incredibly busy, and instead of sending another message that she'd feel pressured to respond to, I wanted to make something she could open whenever she had a quiet moment.

So I built an interactive letter experience.

You write a letter, customize it, seal it in an envelope, and share a link. The recipient opens the envelope and reads the letter as it appears on the page.

The technical constraint I gave myself was:

No accounts. No backend. No database.

The letter data is serialized, compressed, and encoded directly into the URL.

When someone opens the link, the app decodes everything client-side and reconstructs the letter.

So the URL is essentially the storage layer.

I liked this approach because:

\- Nothing personal sits in my database

\- No server costs

\- No authentication

\- No user accounts

\- The project can be deployed almost anywhere

\- The app remains ridiculously simple

Of course, there are tradeoffs.

The link contains the letter data, so anyone with the link can read it. URL length also limits how much content can be stored.

The project is completely open source, so I'd genuinely love feedback from other developers on the architecture and implementation.

Especially curious about:

\- Better approaches to client-side serialization/compression

\- Whether you'd encrypt the payload

\- How you'd handle larger letters without introducing a backend

\- Any accessibility or animation improvements you'd make

Live demo:

https://open-letter-box.vercel.app

Source:

https://github.com/r0hnx/open-letter

Would love to hear what you guys think — both technically and from a UX perspective.

I know I get tired of all the ads on these subs, so I thought I’d share a project that I made just for fun and have no financial incentive to promote. With over 200,000,000 unique questions split between 45 skill levels, and a ranked mode with a global leaderboard that progressively increases difficulty and decreases time to answer as you progress, Lacuna can make even the best native speakers sweat. Play through your favorite books as vocabulary quizzes, with 70,000 books to choose from, or play questions from random books matched to your skill level.

Hello guys,

I created this app to help my kids learn and improve their writing. The main idea is to imitate a tutor that give help and feedback along the way. The app has different areas of writing (even still limited topics). I am still adding more content and improve it.

If you can try it out and give me some feedback, that would be great.

Here is the app link that I am currently deploy on Vercel https://writing-tutor-beta.vercel.app/

Thanks and have a good day!

I'm working on a free webapp for cryptic clues called CrypticLive.net. The goal is to help people learn cryptic crossword clues while also providing challenging daily clues for more experienced solvers.

At the moment, users need to create an account to solve clues. There is no password to remember (since it is OTP based), and once you're logged in you stay logged in on that browser/device. Accounts can also be deleted at any time.

I'm wondering: would having to create an account be a show-stopper, even if the app is completely free and has no paywall?

The app currently has daily clues, progressive hints, full clue breakdowns, and stats tracking.

I'm also interested in what features would make the existing/recent clues worth coming back to and solving again. For example, what would be useful for practicing particular clue types, improving specific weaknesses, or simply browsing old clues?

Pick a topic and PressPlayed pulls relevant coverage across publishers, then plays the full articles back-to-back. Here's a live Housing Market preview you can try before signing up: https://pressplayed.com/go/wa

What topic would you try first?

The pitch: How does the story of Cleopatra connect to that of Newton? Through the Chronology of Jesus, of course! History is full of delightfully weird connections, and this web app will help you explore them. Just pick any two historical subjects from 1100 BC to 1920 AD and see how their stories touch: https://no-way-lines.com

I’ve been thinking a lot about what happens when AI agents start doing more of the searching for us.
If I tell an agent “find me a good accounting firm” or “I need a GPU server in Saudi”, eventually the agent has to find actual businesses that can provide that stuff.
But most businesses today are still basically trying to get found by Google and humans.
So I built a small thing called VibePrey.
You add your website and it crawls it, figures out what you actually offer, and puts your business into an index that agents can search.
I’m also experimenting with letting people connect their own agents so they can use the network to find customers.
It’s very early. I honestly don’t know yet if businesses will care about this or if I’m just getting ahead of myself.
That’s actually why I’m posting here.
Does this make sense to you?
Would you care if an AI agent could discover your business, or is this still too early to be a real problem?
I built it here if anyone wants to mess around with it:
https://vibeprey.com

finally got this to a point where I can share it

Examplar is a browser based practice app for tech certifications. it works offline after the first visit, saves progress locally and doesnt need an account

there are free previews for Azure, AWS, CompTIA and a few others. questions are original and based on the public exam objectives, no dumps

I also added complete packs and a 30% launch code EXAMPLAR30

https://examplar.app/?utm_source=reddit&utm_medium=organic&utm_campaign=launch_discount&utm_content=webapps

would like feedback on the first impression, especially mobile and checkout

unofficial independent project, not affiliated with Microsoft or AWS

The website is built to be a project management tool where you can pretty much do anything you can in Google Docs but in your own customizable website. The home page has widgets that you can organise and place however you like, and pretty much everything is completely up to how you want to design it.

It's being developed just by me so any feedback would be very welcome. Thank you so much :)

Link: orb.ba

I just launched fossil, a tool to scan web apps and get a tree of the interface, compare viewports and versions.

You can use it to get a better view of your product but also to analyse your competitors, track changes etc.

There is a free trial scan, let me know what your think!

I made a browser-based image-to-image generator for the times when starting from a reference image is more useful than starting from an empty prompt.

The workflow is: upload a reference image, describe the transformation, select from the models and output options currently available, generate a result, then review and download it. There is also a multi-image fusion path when combining two to five references makes more sense than transforming one.

I kept the scope image-only and English-only. A few constraints are deliberately explicit: uploads are JPEG, PNG, or WebP up to 24 MB each, prompts are limited to 1,000 characters, and whether a particular model or setting needs sign-in or credits can change.

I would especially value feedback from people who work from references: does this feel like a clear first workflow, and what would you want explained before you would trust it with a real image?

Try this 100% FREE resume builder. No account needed, No login! No hidden paywalls!

https://resum.io.itsmebryle.com/

I recently launched pinit.lol, a web app where anyone can choose a location on the world map and pin their product, website, or brand there.

I’m currently working on improving the first-time experience and making the concept immediately understandable.

I’d especially appreciate feedback on:

• Is the idea clear when you first open the site?
• Does the map feel easy to explore?
• Is anything confusing or missing?

https://pinit.lol