Try Convi

Conversational Spanish, Swedish and German for people who are about to be in the country. The lines you actually need at a bar, in a taxi, or looking for the metro, rather than the ones a textbook opens with.

Live: tryconvi.com

Three editions ship: Spanish as spoken in Spain, Swedish as spoken in Stockholm, and German. Every scenario is a real exchange — what you say, and what comes back at you — and every target-language line can be played aloud.

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What is interesting in here

Not the CRUD. These are the problems that took real work:

A multiple-choice question with two right answers cannot be answered. Distractors are drawn from the same deck as the answer, so sooner or later one of them is the answer in different words: "A beer, please" against "A small beer, please" are both what ¿Una caña porfa? means. String equality does not catch that. tooAlike tests two shapes of the failure — one line containing all of another's words, and heavy overlap without containment — while leaving genuine contrasts ("Draft, thanks" / "Bottle, thanks") alone. Options are then built under tiered guards that are given up one at a time, because a stage with three items still has to fill four boxes.

Analytics that can count returning visitors without knowing who they are. The only thing every page view carries is an IP address, which is personal data. It is hashed with a secret salt on arrival and only the hash is stored, under a key that deletes itself after thirty quiet days. The salt is the part that matters: unsalted, an IP hash is not anonymous at all — there are only four billion addresses, so anyone holding the hashes could reverse them in an afternoon. See src/lib/visitor.ts.

A paywall that can be switched off without being deleted. PAYWALL_ENABLED is one boolean in a dependency-free module that both the server and the browser can read. Turning it off left the Gumroad product, the signed entitlement cookie, the device limit and the webhook entirely intact — so the decision is reversible in one line rather than in a revert of forty commits.

Speech that survives a network that cannot reach the model host. Lines are spoken from generated clips where they exist and the device's own voice where they do not. Generating them means reaching a speech endpoint (Edge TTS by default), which the development sandbox cannot do — so a GitHub Actions workflow does it on a runner: audition attaches samples of every candidate voice to the run, and record re-records a whole edition in the one you pick and commits it. The voice picker is scored by name, after discovering that preferring localService voices reliably selected the worst voice on the machine: on every desktop platform the local voices are the old ones.

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Architecture in one paragraph

Scenario pages are prerendered at build time, because they are what search engines and answer engines read. Practice is server-rendered and pulls its deck from /api/quiz-items, so the content never ships in the client bundle. Content is authored as JSON per locale rather than in a CMS — it is edited far less often than it is read, and keeping it in the repository means a content change is reviewed like a code change and tested by the same suite.

Fuller notes in ARCHITECTURE.md.

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Running it

npm install
cp .env.example .env   # every value is optional for local development
npm run dev            # http://localhost:4321

Command	What it does
npm run dev	Dev server
npm test	57 tests over the quiz engine
npm run test:watch	The same, on change
npx astro check	Typecheck, including .astro files
npm run build	Production build

Nothing needs a key to run. Without Redis the rate limiter and the usage counters both fail open; without a TTS key the device voice reads the lines. Every variable is listed with no values in .env.example.

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Tests

npm test

They run against the decks that actually ship, so a content edit that reintroduces two interchangeable answers fails here rather than reaching a learner — which is how the ¿Una caña porfa? question got in front of someone in the first place.

Each test was checked by breaking the thing it guards and confirming it went red. Two of them turned out to be decorative and were rewritten: one compared answers with an equality that could never catch a near-duplicate, and another allowed a 2% clash rate against a real rate of 0.00%, so deleting the entire separation pass still passed. An allowance nobody measured is indistinguishable from no test at all.

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Stack

Astro 7 (SSR + prerendering, @astrojs/vercel) · React 19 islands · TypeScript, strict, no any · Upstash Redis · Vercel · Edge TTS / Google / Azure / Piper TTS · Vitest

Built with AI, and not quietly

Written solo, using Claude Code as a pair-programmer. I chose the architecture, reviewed every change and rejected plenty; the commit history is unedited and shows exactly who wrote what. The interesting parts above are the ones where the first answer was wrong and the second was found by testing it.

Licence

Two licences, because there are two kinds of work here.

• Source code — MIT. Everything outside content/ and public/audio/. Take it and build on it.
• Language content — all rights reserved. The phrases, translations, scenarios and recordings are the product rather than the scaffolding, and they are not open source. Permission for teaching or research is genuinely available — ask.