DEV Community: Tony

I run 17 AI tools on Supabase Edge Functions + Gemini 2.5 Flash. My monthly cost? Less than a coffee.

Tony — Tue, 28 Apr 2026 14:46:36 +0000

Here's the exact stack, with code you can copy.

Why this combo wins
Need SolutionCost
Database + Auth Supabase Free tier covers a lot
AI inference Gemini 2.5 Flash ~$0.075/M input tokens
Server compute Edge Functions Free 500k invocations/mo
Rate limiting Postgres table Free
Sharing images Edge Function + SVG Free
No Vercel pro. No OpenAI bill. No Redis. Just Supabase and a free Google AI Studio key.

The pattern (one Edge Function, all your AI)
// supabase/functions/ai-task/index.ts
import "https://deno.land/x/xhr@0.1.0/mod.ts";
import { createClient } from 'jsr:@supabase/supabase-js@2';

const corsHeaders = {
'Access-Control-Allow-Origin': '*',
'Access-Control-Allow-Headers': 'authorization, content-type',
};

Deno.serve(async (req) => {
if (req.method === 'OPTIONS') return new Response(null, { headers: corsHeaders });

const { prompt, taskType } = await req.json();

// 1. Rate limit (atomic via Postgres)
const supabase = createClient(
Deno.env.get('SUPABASE_URL')!,
Deno.env.get('SUPABASE_SERVICE_ROLE_KEY')!
);

const userId = req.headers.get('x-user-id');
const { data: rl } = await supabase.rpc('check_rate_limit', {
p_user_id: userId,
p_function: taskType,
p_max: 10,
});

if (!rl.allowed) {
return new Response(JSON.stringify({ error: 'Rate limited' }), {
status: 429, headers: corsHeaders
});
}

// 2. Call Gemini
const aiResponse = await fetch(
https://generativelanguage.googleapis.com/v1beta/models/gemini-2.5-flash:generateContent?key=${Deno.env.get('GEMINI_API_KEY')},
{
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({
contents: [{ parts: [{ text: prompt }] }],
generationConfig: { temperature: 0.7, maxOutputTokens: 2048 },
}),
}
);

const data = await aiResponse.json();
const text = data.candidates?.[0]?.content?.parts?.[0]?.text ?? '';

return new Response(JSON.stringify({ text }), {
headers: { ...corsHeaders, 'Content-Type': 'application/json' }
});
});
The atomic rate limiter (Postgres FTW)
create table rate_limits (
id uuid primary key default gen_random_uuid(),
user_id uuid not null,
function_name text not null,
request_count integer default 1,
window_start timestamptz default now()
);

create or replace function check_rate_limit(
p_user_id uuid, p_function text, p_max int
) returns json language plpgsql security definer as $$
declare
v_count int;
begin
-- Clean old windows (>1h)
delete from rate_limits
where user_id = p_user_id and function_name = p_function
and window_start < now() - interval '1 hour';

-- Count current
select coalesce(sum(request_count), 0) into v_count
from rate_limits
where user_id = p_user_id and function_name = p_function;

if v_count >= p_max then
return json_build_object('allowed', false, 'used', v_count);
end if;

insert into rate_limits (user_id, function_name) values (p_user_id, p_function);
return json_build_object('allowed', true, 'used', v_count + 1);
end;
$$;
Why it's atomic: the delete + insert happen in a single transaction. No race conditions, no Redis needed.

The cost breakdown (real numbers)
For ~50,000 AI requests/month:

Gemini 2.5 Flash: ~$3.50 (mostly input tokens)
Supabase Free tier: $0 (covered by free quota)
Edge Function invocations: $0 (under 500k limit)
Total: ~$3.50/month for production AI.

If I needed image gen, I'd add Lovable AI's free gemini-2.5-flash-image-preview and pay even less.

Gotchas I hit
No external Deno deps in Edge Functions. Use crypto.subtle natively. External imports cause bundling failures.
Set verify_jwt = false for public-facing functions in supabase/config.toml, or your unauth users get 401s.
Use service role key on the server, never on the client. Always.
Try the stack live
All 17 tools running this exact stack: codemasterip.com

Drop a ⭐ if this helped, and let me know what you'd build with it.

I made an AI that roasts your code (and it's brutally honest)

Tony — Mon, 27 Apr 2026 05:35:37 +0000

We've all been there: you push code thinking it's clean, then a senior dev comments "why?" on line 47 and your soul leaves your body.

I built Code Roast to give you that experience before the PR — for free, with AI, in 15 languages.

The brief
Build an AI code reviewer that's funny, honest, and educational.
Bonus: it should hurt a little (so you remember the lesson).

The result
You paste code → the AI returns:

A roast ("This 47-line function violates SRP harder than my New Year's resolutions")
A severity badge (mild → catastrophic) you can share
Actionable fixes (because being mean isn't useful without solutions)
The prompt that makes it work
After 30+ iterations, this is the structure that consistently produces funny + useful:

const prompt = `You are a senior dev reviewing code for a junior. Be:

BRUTAL but FAIR (no personal attacks, only the code)
SPECIFIC (cite line numbers, name the antipattern)
CONSTRUCTIVE (every roast = one concrete fix)
FUNNY (one joke max, never at the dev's expense)

Return JSON:
{
"severity": "mild" | "medium" | "spicy" | "catastrophic",
"roast": "<2-3 sentences, the funny part>",
"issues": [{ "line": number, "problem": string, "fix": string }],
"verdict": ""
}

Code to review:
`\
${userCode}
\``;
The key insights:

Constraint produces creativity. "One joke max" forces the model to pick the best one.
Structured output > prose. JSON makes the UI predictable and shareable.
Severity as enum lets us show different badge designs (and a different Kody face per level).
The tech stack (boring on purpose)
Frontend: React + Vite + Tailwind
AI: Gemini 2.5 Flash via Supabase Edge Function
Rate limiting: Postgres rate_limits table, 5 roasts/hour for free, unlimited Pro
Result sharing: dynamic 1200×630 SVG generated in another Edge Function
The whole thing is ~400 lines of code for the feature itself.

What surprised me

Severity badges drive 80% of the shares.
People love showing off a "Catastrophic 🔥" badge to their friends way more than the actual review. Make the outcome shareable, not the process.
Multilingual roasts hit different.
A Spanish dev got a roast that included a "madre mía" and tweeted it. Localized humor > translated humor.
Free tier converts.
About 4% of users hit the free limit and upgrade. The tool itself is the funnel.

Try it (free, no signup needed)
👉 codemasterip.com/code-roast

Paste your worst code. I dare you.

Have you built AI tools that lean into humor? What worked for you? Comments are open.

I built 17 AI tools for developers in 4 months. Here's what I learned about shipping fast.

Tony — Sat, 25 Apr 2026 02:08:21 +0000

From idea to 17 production AI tools using Gemini, Supabase Edge Functions, and a brutal focus on shipping. Real numbers, real mistakes, real lessons.

Four months ago I had an idea: what if devs could roast their own code with AI, calculate their market salary, simulate interviews, and learn programming — all in one place, all free, all multilingual?

Today CodeMasterIp has 17 production AI tools, runs in 15 languages, and serves thousands of devs. Here's what I learned shipping that fast.

Pick the boring stack on purpose I went with React + Vite + Supabase + Gemini 2.5 Flash via Edge Functions. Nothing exotic. No K8s. No microservices.

Why? Because the bottleneck was never tech — it was always deciding what to build next.

// One Edge Function. One model. One pattern. Repeat 17 times.
const response = await fetch(
'https://generativelanguage.googleapis.com/v1beta/models/gemini-2.5-flash:generateContent',
{
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({ contents: [{ parts: [{ text: prompt }] }] }),
}
);
That's it. That's the architecture for all 17 tools.

Each tool ships as a "complete product" Every tool has its own URL, its own OG image, its own shareable result page. Why? Because a tool that can't be shared on Twitter doesn't exist.

/code-roast → AI roasts your code with severity badges
/salary-calculator → market salary with country adjustments
/dev-quiz → "what dev are you" personality test
/typing-speed → WPM ranks for coders
/dev-bingo → bingo card with dev clichés
Each one has a /result/:id page that generates a custom 1200×630 SVG card via Edge Function. Twitter, LinkedIn, Reddit — all eat them up.

Free is not a strategy. It's the strategy. Most tools competing with mine charge $9/mo. Mine are free. Why?

Because attention is the bottleneck, not money. A free tool that 10,000 people share beats a $9 tool that 200 people pay for — every time.

Monetization comes from the one thing people pay for: the AI chat with persistent context.

Internationalization from day 1 15 languages. react-i18next. Every tool, every page, every error message. The code? Pre-rendered in 12 languages inside blocks for SEO.

Aprende programación con IA

Learn programming with AI

用AI学编程

Result: traffic from countries I didn't even target.

The most underrated growth lever: programmatic SEO I generated 45,000 unique URLs programmatically by combining:

12 languages × 200 topics × 18 page types
Each one has unique content, unique meta tags, unique JSON-LD. Each one pings IndexNow on creation.

Most never rank. Some rank #1 for long-tail queries I never imagined.

Mistakes I made (so you don't have to) Built ads first, removed them later. AdSense killed page speed and SEO. -40% LCP. Removed everything. Tried Reddit autopromo. r/learnprogramming closed my post in 2h. Lesson: provide value first, sell later. Over-engineered auth early. Supabase auth + Google OAuth = 30 minutes. Done. What I'd do differently Ship the first tool in a weekend. Not 4. Not 17. One.

The 17 came from compounding learnings: each tool was 30% faster to build than the previous one because the patterns repeated.

If you want to see all 17 tools in action: codemasterip.com. The Code Roast one is the most fun — paste any code and the AI will tell you what's wrong with it (with severity levels, like a real code review).

What would you build with this stack? Drop it in the comments — I'm curious.