DEV Community: Chad Brunswick

Which AI Model Are You? I built a personality quiz and people can't stop sharing

Chad Brunswick — Sat, 28 Mar 2026 08:03:36 +0000

I made a quick personality quiz: Which AI Model Are You?

7 questions about how you think, work, and communicate. At the end you find out if you're GPT-4o (The All-Rounder), Claude (The Thoughtful One), Gemini (The Overachiever), Llama (The Free Spirit), Mistral (The Dark Horse), or GPT-4o Mini (The Budget King).

Why it works

Each result has its own color scheme, emoji, personality description, and trait badges. The result card is designed to be screenshotted — which is exactly what people do.

The questions map to real differences between the models: how they handle uncertainty, communication style, what they prioritize. It's tongue-in-cheek but surprisingly accurate.

How I built it

Single HTML file. Vanilla JS. No framework, no backend, no build step. The scoring system gives each answer weighted points toward different models, and whichever model has the highest score at the end wins.

Options are shuffled per question so you can't pattern-match your way to a specific result.

The whole thing is under 15KB.

Try it

https://billion-whichai.pages.dev

Takes about 60 seconds. I'm curious which model you get — and whether you agree with the result.

I also have a bunch of other free browser games and AI tools if you're into that sort of thing.

I built 6 browser games you can play right now — no download, no signup, no ads

Chad Brunswick — Sat, 28 Mar 2026 02:09:12 +0000

I've been building free browser tools and recently started making games too. They're all single HTML files — no frameworks, no npm, no backend. Here are the ones I'm most proud of:

1. Which AI Model Are You?

7 questions to find out if you're GPT-4o, Claude, Gemini, Llama, Mistral, or GPT-4o Mini. Each result has its own color scheme, traits, and personality description. Shareable result card.

This one's been getting the most engagement so far — people love finding out which model matches their personality.

Take the quiz

2. MASH Game

Remember MASH from school? Mansion, Apartment, Shack, or House. Pick your options for partner, job, city, car, and number of kids — then watch the elimination happen live.

The twist: if you have an OpenAI or Gemini API key, it'll write a funny AI-generated story about your predicted future.

Play MASH

3. AI Mind Reader (20 Questions)

Think of anything — a person, animal, place, object, or fictional character. The AI asks 20 yes/no questions and tries to guess what you're thinking. It's like Akinator but powered by GPT or Gemini.

Needs an API key (OpenAI or Gemini). Each game costs about $0.01.

Play Mind Reader

4. Spacebar Speed Test

How fast can you press the spacebar? Four modes: 1 second, 5 seconds, 10 seconds, 30 seconds. Challenge friends with a shareable link that includes your score.

This was inspired by the TikTok spacebar challenge. Average is about 6-7 SPS.

Play Spacebar Counter

5. Human or AI?

10 rounds of text — some written by humans, some by AI. Can you tell the difference? It's harder than you think.

Play Human or AI?

6. Daily Math Puzzle

Like Wordle but for math. Combine 6 numbers using +, -, x, / to reach the target. New puzzle every day.

Play Daily Math

All of these run in your browser. No downloads, no accounts, no tracking. View source on any of them — they're vanilla HTML/CSS/JS.

I also have a bunch of free AI tools (text rewriter, translator, summarizer, agent builder) if you're into that.

What should I build next?

I replaced 5 Fiverr gigs with AI tools that cost $0.01 each

Chad Brunswick — Fri, 27 Mar 2026 20:39:27 +0000

I've been freelancing for a few years and kept noticing the same thing: most AI writing gigs on Fiverr are just someone pasting your brief into ChatGPT and charging $20-200 for it.

So I built free alternatives where you bring your own API key and cut out the middleman entirely.

The tools

Product Description Generator — Paste product features, pick a style (Amazon, Shopify, luxury, social), get 3 variations. Fiverr: $20-50. BYOK: $0.01.

Ad Copy Generator — Enter your product + audience, get Facebook ads, Google ads, Instagram captions. Fiverr: $50-200. BYOK: $0.02.

SEO Article Writer — Enter a keyword, get a full blog post with headings + meta description. Agencies: $50-150. BYOK: $0.05.

Cold Email Generator — Describe what you sell and who you're targeting. Get a 3-email sequence. Consultants: $100+. BYOK: $0.02.

Social Media Post Generator — Enter brand + theme, get a week of posts for any platform. Managers: $500-2K/mo. BYOK: $0.05/week.

How it works

You paste your OpenAI or Google Gemini API key (stored in your browser, never sent to my servers). Pick a model — GPT-4.1 Nano for cheap, GPT-4o for quality. Hit generate.

The output uses the same frontier models that power the expensive SaaS tools, but you pay the API provider directly. No subscription, no word limits, no markup.

The math for freelancers

If you're selling writing services, these tools are even more useful. Generate in seconds, review and polish, deliver to client. Your cost: $0.01-0.20. Client pays: $20-200. You keep the margin and the time.

Try them

All free, all BYOK, all run in your browser: billion-hub.pages.dev

I also built an AI Agent Builder with 4 research-backed strategies and a Text Rewriter that does what QuillBot does but with no word limits.

5 AI tools that replace $20 Fiverr gigs for $0.01 each (BYOK, free, no signup)

Chad Brunswick — Fri, 27 Mar 2026 18:46:07 +0000

I've been building BYOK (bring your own key) AI tools — free web apps where you paste your OpenAI or Gemini API key and get the same output that Fiverr freelancers charge $20-200 for.

The cost difference is absurd.

The tools

Product Description Generator — Paste product features, pick a style (Amazon, Shopify, luxury, social), get 3 description variations. Fiverr price: $20-50 for 5 descriptions. BYOK cost: $0.01.

Ad Copy Generator — Enter your product + target audience, get Facebook ads, Google ads, Instagram captions, LinkedIn posts. Fiverr price: $50-200 per ad set. BYOK cost: $0.02.

SEO Article Writer — Enter a keyword, get a full SEO-optimized blog post with headings + meta description. Content agencies charge $50-150 per article. BYOK cost: $0.05-0.20.

Cold Email Generator — Describe what you sell and who you're targeting. Get a 3-email outreach sequence (initial + follow-up + final touch). Sales consultants charge $100+ for this. BYOK cost: $0.02.

Social Media Post Generator — Enter your brand + theme, get a week of posts for any platform. Social media managers charge $500-2K/month. BYOK cost: $0.05 per week.

Why BYOK?

These tools use GPT-4o or Gemini — the same models that power the expensive SaaS tools — but you pay the API provider directly. No subscription. No word limits. No middleman markup.

A Fiverr freelancer using ChatGPT to write your product descriptions is charging you $20 for something that costs them $0.01. These tools cut out that margin entirely.

The math

If you're a freelancer yourself, these tools are even more powerful. Generate the output in seconds, review and polish it, deliver to your client. Your cost: $0.01-0.20. Your client pays: $20-200. That's a 1,000-10,000x margin.

Try them

All free, all run in your browser, all BYOK: billion-hub.pages.dev

I also built an AI Agent Builder with 4 research-backed strategies (Plan & Execute, ReAct, Reflection, Fast Mode) and an AI Text Rewriter that does what QuillBot does but with frontier models and no word limits.

I built a free text rewriter with no word limits — uses GPT-4o, not a proprietary model

Chad Brunswick — Fri, 27 Mar 2026 17:30:28 +0000

Every paraphrasing tool online has the same problem: word limits.

QuillBot caps you at 125 words on the free tier. Grammarly makes you sign up. Scribbr puts a banner over your output. They all use their own proprietary models that are... fine. Not great.

So I built an alternative that uses GPT-4o or Gemini — the actual frontier models — and has no word limits at all.

AI Text Rewriter — Free, BYOK, No Limits

How it works

Paste your API key (OpenAI or Google Gemini)
Paste your text
Pick a style: Standard, Formal, Casual, Simpler, Shorter, Expand, or Academic
Hit Rewrite

That's it. The rewrite uses whichever model you selected. GPT-4.1 Nano costs about $0.001 per rewrite. GPT-4o costs maybe $0.01 for a long paragraph. No word limits, no signup.

Why BYOK matters here

QuillBot uses its own model. It's decent for basic paraphrasing but falls apart on nuanced text — academic writing, technical docs, anything with domain-specific language.

GPT-4o and Gemini 2.5 Pro are just better at this. They understand context, preserve meaning, and produce natural-sounding output. The tradeoff: you need an API key. But if you already have one (and most developers do), this is strictly better.

The build

One HTML file. 31KB. Everything runs in your browser — your text goes directly to OpenAI or Google, never to my servers. No backend, no database, no tracking.

I also built an AI Agent Builder with the same BYOK approach — paste a key, define a goal, watch an autonomous agent work through it.

Try it

billion-rewriter.pages.dev

The "Academic" style is surprisingly good for cleaning up first drafts. And "Shorter" is perfect for cutting bloated emails in half.

I built a free AI agent builder with 4 research-backed strategies (runs in your browser, BYOK)

Chad Brunswick — Fri, 27 Mar 2026 17:12:55 +0000

I wanted a way to run an AI agent loop without installing anything, managing dependencies, or paying for a SaaS subscription. So I built one that runs entirely in your browser.

AI Agent Builder — Free, BYOK, No Backend

What it does

Paste your OpenAI or Gemini API key, type a goal, and watch an autonomous agent work through it step by step. The agent plans, executes, and verifies — all client-side. Your key goes directly to the API provider, never to my servers. There is no backend.

Four strategies based on real research

The tool implements four proven agentic loop patterns from Anthropic, OpenAI, and Google DeepMind research:

Plan & Execute — breaks the goal into steps, executes each one, then verifies. Best for structured tasks like research or content creation.

ReAct (Reason + Act) — the agent thinks, acts, observes, and adapts on every iteration. From the original Princeton/Google Brain paper. Best for open-ended exploration where you don't know the steps upfront.

Reflection Loop — generates a draft, critiques it, then improves. Repeats up to 3 times. Based on Reflexion (Northeastern/MIT) which hit 91% on HumanEval. Best for writing and code.

Fast Mode (ReWOO) — plans everything in one call, executes in one call. Just 2 API calls total. Best for simple tasks when you want to save money.

The build

One HTML file. 54KB. Vanilla JavaScript. No React, no build step, no npm. Hosted on Cloudflare Pages free tier.

The hardest part was getting the ReAct loop to parse reliably — the model needs to output structured "Thought → Action → Observation" blocks, and different models format them differently. I ended up parsing for "Final Answer:" as the termination signal, which works across GPT-4o and Gemini.

Cost tracking

Every API call shows token usage and estimated cost in real-time. A typical 5-step agent run costs $0.01-0.05 with GPT-4.1 Nano. You can watch the cost accumulate and kill the run if it gets expensive.

Try it

billion-agentbuilder.pages.dev

Give it something like "Research the pros and cons of Rust vs Go for backend development" and watch it work. The ReAct strategy is the most fun to watch — you can see the agent reasoning in real time.

Curious which strategy works best for your use case. I've been defaulting to Plan & Execute but the Reflection loop produces noticeably better writing.

10 Free Browser Tools Every Developer Should Bookmark (No Signup, No Ads)

Chad Brunswick — Fri, 27 Mar 2026 14:03:52 +0000

I keep bookmarking web tools and then forgetting where I saved them. So I started collecting the ones I actually use into a single page.

Here are 10 that I reach for constantly — all free, all run in-browser, no signup needed.

Developer Tools

1. JSON Formatter & Validator
Paste JSON, get it pretty-printed with syntax highlighting. More importantly: it tells you exactly where the error is, with line and column numbers. Better than most VS Code extensions for quick validation.

2. Base64 Encoder/Decoder
Text, files, and JWTs. The JWT decode mode saves me from going to jwt.io every time I need to inspect a token. Drag-and-drop file encoding is a nice touch.

3. AI Token Counter
Paste a prompt, see estimated token counts for GPT-4o, Claude, and Llama. Shows cost estimates too. Essential if you're building anything with LLM APIs and trying to stay under budget.

4. Link Preview Checker
See how your Open Graph tags will render on Google, Twitter, Discord, WhatsApp, LinkedIn, Slack, and iMessage — all at once. Saves you from deploying, sharing to a test channel, deleting, and repeating.

5. QR Code Generator
No watermark, no email, no "premium tier." Just paste text, get a QR code, download as PNG.

Productivity Tools

6. Word Counter
Words, characters, sentences, paragraphs, reading time. I use this for blog posts and documentation where length matters.

7. Unit Converter
Length, weight, temperature, speed, area, volume. Shareable conversion URLs — handy for Slack messages.

Fun / Challenge Tools

8. Reaction Time Test
Tap when the screen turns green. Average is 250ms. My best is 214ms. There's a challenge link feature — I've started a minor war in my team's Slack.

9. Typing Speed Test
Real text passages, not random words. WPM + accuracy. Also has challenge links.

10. Daily Math Puzzle
Combine 6 numbers to reach a target. New puzzle every day. Basically Countdown (the British game show) in your browser. Warning: addictive.

All of these are on one page if you want to bookmark just one thing: billion-hub.pages.dev

What browser tools do you use daily? Always looking for more to add.

I built a typing speed test in a single HTML file (23KB, zero dependencies)

Chad Brunswick — Fri, 27 Mar 2026 13:54:45 +0000

I've been building single-file web tools that work entirely in the browser. Zero npm, zero frameworks, zero backend. My latest: a typing speed test.

How Fast Can You Type? — Free Typing Speed Test

What it does

10 different real text passages (no lorem ipsum)
Real-time character highlighting — green for correct, red for errors
Timer starts on first keystroke
Shows WPM, accuracy, and a rating (Legendary / Fast / Average / Slow)
Challenge friends with a shareable link that shows your score

The build

One HTML file. 23KB total. Vanilla JS. Hosted on Cloudflare Pages free tier.

The hardest part was handling mobile keyboards correctly — turns out you need a hidden input element to trigger the soft keyboard, and then mirror keystrokes to the display. CSS user-select: none on everything except the hidden input, or autocorrect will fight you.

Try it

billion-typingtest.pages.dev

I scored 87 WPM. The average is 40-60. Would love to know where you land — there's a "Challenge a Friend" button that generates a compare link.

8 Free Web Tools I Built — No Ads, No Signup, No Tracking

Chad Brunswick — Fri, 27 Mar 2026 12:07:52 +0000

Over the past few weeks I've been building small, free web tools — the kind of thing I always wished existed without the signup wall, the ads, or the tracking.

They're all vanilla HTML/CSS/JS. No frameworks, no accounts, no data collection. Everything runs in your browser.

Here's the full collection:

The Tools

Word Counter — Paste text, get word count, character count, sentence count, and estimated reading time.

JSON Formatter — Paste JSON, get it pretty-printed with syntax highlighting. Shows you exactly where the error is if it's invalid.

Base64 Encoder/Decoder — Encode text, decode strings, handle files and JWTs. Supports URL-safe mode.

QR Code Generator — Paste any text or URL, download the QR code as PNG. No watermarks.

Unit Converter — Length, weight, temperature, speed, area, volume. Instant conversion.

Reaction Time Test — Test your reflexes. Average is 250ms. Can you break 200? Challenge your friends with a shareable link.

Typing Speed Test — How fast can you type? Get your WPM score and challenge friends to beat it.

Color Personality Quiz — 5 quick questions to find out your personality color. Surprisingly addictive.

Why?

Every time I needed a QR code or wanted to format some JSON, I'd land on a site that wanted my email or was plastered with ads. These tools cost nothing to host (Cloudflare Pages free tier) and nothing to use.

Browse them all: billion-hub.pages.dev

Every Free QR Code Generator Is Terrible So I Built One

Chad Brunswick — Fri, 27 Mar 2026 11:46:54 +0000

I needed a QR code last week and every "free" generator online wanted my email, showed me 3 ads, or watermarked the output.

So I built one that does none of that.

QR Code Generator — Free, instant, no signup

Paste a URL or any text, get a QR code. That's it. No account, no watermark, no tracking.

What it does

Generates QR codes from any text or URL
Download as PNG
Works on mobile
Dark theme because it's 2026

The stack

One HTML file. Zero dependencies. Hosted on Cloudflare Pages (free tier). Total size: under 20KB.

Sometimes the simplest tool is the one that's missing.

Try it: billion-qrcode.pages.dev

I built a unit converter with zero dependencies (no ads, no frameworks)

Chad Brunswick — Fri, 27 Mar 2026 02:56:34 +0000

I've been annoyed by unit conversion sites for years. They're slow, covered in ads, and half of them require JavaScript frameworks just to multiply a number by 2.54.

So I built a dead-simple unit converter — no ads, no tracking, no frameworks. Just a single HTML file that does the math instantly.

What it converts

Length: mm, cm, m, km, in, ft, yd, mi
Weight: mg, g, kg, t (metric tons), oz, lb
Temperature: Celsius, Fahrenheit, Kelvin
Volume: mL, L, tsp, tbsp, fl oz, cup, pt, qt, gal
Area: cm², m², km², in², ft², ac, mi²
Speed: m/s, km/h, mph, knots
Data: bits, bytes, KB, MB, GB, TB

It also includes a data size converter, which I couldn't find anywhere as a standalone tool without it being buried 3 clicks deep.

Why no framework?

The whole thing is ~400 lines of vanilla HTML/CSS/JS. Loads in under 100ms even on a slow connection. No npm, no build step, no dependencies. Just open it and it works — including offline once cached.

I'm old enough to remember when the web was like this everywhere. Trying to bring that back, one tiny tool at a time.

Try it

billion-unitconverter.pages.dev

Type a value, pick a category and unit, and the conversions appear instantly. No submit button. No loading spinner.

Source is a single HTML file if you want to fork it or host it yourself.

I Can't Get Below 200ms — Can You?

Chad Brunswick — Fri, 27 Mar 2026 02:54:52 +0000

My personal best is 214ms. I've tried 47 times today. I cannot crack 200ms no matter what I do.

A colleague swore he got 183ms last week. I accused him of cheating. He said I'm just old.

So I built this: Reaction Time Test

How it works

You wait for the screen to flash green, then tap/click as fast as humanly possible. Five rounds. It averages your best attempts and rates you on a scale:

🟣 Superhuman — under 150ms (allegedly possible)
🟢 Fast — 150–200ms (pro gamer territory)
🟡 Average — 200–250ms (most people land here)
🔴 Slow — 250ms+ (welcome to the club)

I keep landing solidly in Average. It's humbling.

What I learned building this

The hard part wasn't the timer — performance.now() is accurate to microseconds. The hard part was preventing click anticipation. If the delay before the green flash is predictable, humans will start clicking before they see it, producing fake sub-100ms "scores."

The fix: randomize the delay between 1.5 and 4.5 seconds. If you click early, it counts as a false start and resets that round. No cheating.

I also added a subtle red background during the "waiting" phase so you're not staring at a blank screen. Seems obvious in retrospect. First version had a 40% false-start rate. After the visual change: dropped to ~8%.

The game

Go try it: billion-reactiontime.pages.dev

Drop your score in the comments. My 214ms is apparently "Average" and I'm not accepting that.