Why I built this site
I built sdk.ac because I was tired of sending people links to 'free' AI tools that were actually lead-capture funnels. You click Summarize and instead of a summary you get a signup wall, a three-uses-per-day counter, or a checkout page asking for a card 'to verify your identity'. The underlying AI request costs a fraction of a cent, and most of these tools are a prompt template wrapped around a text box. Charging a monthly subscription for that felt wrong, so I made the version I wanted to exist: open the page, type, get a result, leave.
Everything here is free, with no login and no usage counter. There is no account system because there is nothing worth gating behind one. There is no pro tier because these tools are deliberately simple, and a pro tier would just be padding. The site covers its costs with modest advertising and by being cheap to run — a static SvelteKit site on edge hosting costs almost nothing per visitor.
Privacy matters more here than on most sites, because what people paste into a summarizer or an email writer is often exactly the text they would never post publicly: a performance review, a half-finished apology, an internal document. We do not require an account, we do not build a profile of you, and we do not keep an archive of what you typed. The tools are designed so that your input exists for the duration of the request and then it is gone.
What each tool is actually for
The AI Translator is for translation that carries tone, not just vocabulary. Dictionary-style translation gives you technically correct sentences that read like a robot wrote them; this one lets you say 'make it polite', 'make it casual', 'this is a business email' and get a version a native speaker would actually send. The AI Summarizer is its counterpart for length instead of language: paste a long article, a meeting transcript, or a report, and get the argument in a few sentences so you can decide whether the whole thing deserves your time.
The Prompt Builder exists because the gap between a mediocre AI answer and a genuinely useful one is usually the prompt, not the model. It walks you through role, context, task, constraints, and output format, and assembles them into a structured prompt you can paste into ChatGPT, Claude, or Gemini. The Image Prompt Builder does the same for image generators like Midjourney, Stable Diffusion, and DALL-E, where the difference between 'a cat' and a usable prompt is a pile of conventions — style keywords, lighting, composition, aspect ratio — that nobody should have to memorize.
The Code Explainer takes a block of code you did not write — a regex from Stack Overflow, a shell one-liner from a CI config, a function from a codebase you just joined — and explains what it does in plain language. The Email Writer goes the other direction: you give it bullet points and a relationship ('decline politely', 'follow up on an invoice', 'ask my professor for an extension') and it drafts the message so you can edit instead of staring at a blank compose window.
The Hashtag Generator suggests tags for Instagram, TikTok, X, and the rest, mixing large generic tags with smaller specific ones — the mix that actually gets a post discovered instead of buried. The Writing Assistant is the general-purpose one: rewriting, tightening, fixing grammar, shifting tone from casual to formal or back. Eight tools, each aimed at one specific, recurring moment where a blank text box wastes ten minutes of your day.
How these tools are built
The site is a SvelteKit app. Each tool page is server-rendered, so what a search crawler or a reader with JavaScript disabled sees is real content, not an empty div waiting for a bundle. Svelte keeps the client-side payload small — these pages are mostly text and a form, and they should load like it.
The tools themselves are thin by design. Most of the engineering effort went into the prompts and the interfaces, not into infrastructure: figuring out which questions to ask you, in which order, so the assembled request produces consistently useful output. A tool that asks three good questions beats a tool with twenty settings you will never touch.
I add tools slowly, and only when I have personally hit the problem more than once. Every tool here started as something I or someone I know needed in an ordinary week — translating a message to a coworker, summarizing a document five minutes before a meeting, decoding a colleague's regex. If a tool is on this site, it earned its place; nothing here exists to inflate a tools count for search engines.
Honest limitations you should know about
AI output is a draft, not a verdict. Language models produce fluent, confident text whether or not the underlying claim is true, and a wrong answer reads exactly as smoothly as a right one. Summaries can drop the one caveat that mattered. Translations can miss sarcasm, honorifics, or culturally loaded phrasing. The Code Explainer can describe what code usually does while missing what your code actually does in an edge case. Treat every output as a starting point that you — the person who understands the context — review before using.
Some jobs are wrong for these tools regardless of quality. Do not rely on AI translation for contracts, medical instructions, immigration paperwork, or anything where a mistranslated clause has real consequences — pay a professional translator. Do not treat a summary as a substitute for reading a document you will be held accountable for. Do not paste passwords, API keys, or other secrets into any AI tool, including this one; the safest secret is the one that never leaves your machine.
And AI text has a texture. If you send AI-drafted emails unedited, the people receiving them will eventually notice, and it will cost you more credibility than the drafts saved you in time. The tools here are built to give you a good first 80 percent. The last 20 percent — the judgment, the specifics, the voice — has to be yours, and honestly, that is the part worth doing.
What this site is not
This is not a SaaS in disguise. There is no waitlist, no 'book a demo', no newsletter interstitial, and no plan to bolt an account system on later. It is a set of pages that do what they say.
It is also not trying to be everything. There are eight tools, chosen deliberately, plus guides explaining how to get better results from each. If the site grows, it grows a tool at a time, each one held to the same bar: would I use this myself, this week? That bar is the entire product strategy.