Videos

Every demo cut, narrated end to end. Most of them also sit on top of the section they teach — the link under each one takes you there. Start with the explainer; then the concepts track in order; the rest you can watch as reference.

Start here

What Langsys is, the whole setup in one take, and the one idea every language needs — flat sentences.

Watch · 1:17 What is Langsys? An SDK in your app and a hosted Translation Manager: how a phrase registers itself by running, where translations come from, and a blog post published at 09:00 that a reader in Madrid gets in Spanish at 09:03 — no build, no write key. On the page: /learn

Watch · 4:13 Getting started, end to end Create the project and its locales, mint a Read & Write key, install and init the SDK, then watch t(), <Translate>, <Phrase> and <DontTranslate> register their phrases and the app switch to Spanish and French with no reload. On the page: /learn/quickstart

Watch · 1:14 Pluralization Why a sentence changes with its number, why the if (count === 1) that fixes it is English grammar in your code, and how writing the sentence flat gets you every branch in every language. On the page: /learn/concepts/locale-store

The concepts track

Five short modules in order, each assuming the last. No SDK-specific syntax on screen — the same cuts sit on top of the Concepts pages.

Watch · 0:30 The workflow The problem — translation round-trips through a pipeline, and Langsys deletes it. On the page: /learn/concepts/how-it-works

Watch · 0:42 Key files Where a project starts, the key other i18n makes you invent, and what replaces it. On the page: /learn/concepts/token-discovery

Watch · 0:36 The locale store How the active locale is held and switched. On the page: /learn/concepts/locale-store

Watch · 1:30 Keys & environments Why a key that can register can never ship, why read-only is a dead end, and which key goes where — then the 09:00 blog post: what leaves the browser and who registers directly. On the page: /learn/concepts/keys-and-environments

Watch · 0:30 Adding a locale Reaching a new language is a project setting — new phrases translate on arrival, one run fills the rest. On the page: /learn/concepts/adding-a-locale

Svelte, API by API

One cut per primitive on langsys-js-svelte. The other bindings share the same surface; the syntax is what differs.

Watch · 1:00 Svelte: the walkthrough What other i18n makes you keep in step, one call, a locale switch, why flat Spanish is wrong for half your users, and what ICU select does about it. On the page: /learn/sdk/svelte

Watch · 1:09 t(phrase, category, params) Opens on the keys-file problem, then the three arguments, ICU placeholders, plurals. On the page: /learn/sdk/svelte

Watch · 1:06 <Phrase> A sentence with markup inside it, kept as one phrase, and why its params are %name%. On the page: /learn/sdk/svelte

Watch · 1:04 <Translate> One tag registers a whole region, and why a block beats a call per line. On the page: /learn/sdk/svelte

Watch · 0:34 <DontTranslate> Brand names and identifiers held back verbatim, without hoisting them out of the sentence. On the page: /learn/sdk/svelte

Watch · 0:42 Content blocks What a content block is — one section registered as a unit, still made of individually reusable phrases. On the page: /learn/sdk/svelte

Watch · 0:34 Categories Why i18n invented keys, and what replaces them — the same word, two meanings, and the pairs it splits into. On the page: /learn/sdk/svelte

Watch · 0:39 Gender agreement The conditional other i18n leaves in your component, and the branches Langsys generates instead. On the page: /learn/sdk/svelte

Watch · 1:07 Attributes What a half-translated form looks like to the person hitting it, and how one <Translate> reaches placeholders, alt text and aria labels in the same pass. On the page: /learn/sdk/svelte

Watch · 0:46 Numbers & dates Numbers and dates per CLDR — why grouping is a shape and not a separator, and why an order number must be passed as a string. On the page: /learn/sdk/svelte

The Translation Manager

app.langsys.dev with no code on screen — for whoever owns the copy, the languages, the keys and the bill.

Watch · 3:02 Managing translations The Manager on its own, for the person who owns the copy: a machine draft corrected, Update Memory, AI Translate with Auto-next through the queue, Never Translate, and a Translator invited to Spanish only. On the page: /learn/dashboard

Watch · 2:47 Translation memory A second project comes up already full — the corrected cart line with its author’s badge carried over, no model called. Organization-wide, one entry per sentence per language. On the page: /learn/dashboard

Watch · 2:24 AI Translator settings Every switch on the tab, shown: custom-per-project, Use AI Translations, auto-translate on and off, auto-detect holding a phrase that arrives already in Spanish. On the page: /learn/concepts/keys-and-environments

Watch · 1:49 Adding a language German added to a live project: the policy set to ask first, the dialog that prices the existing catalog exactly, and the store switched to German with nothing built or deployed. On the page: /learn/concepts/adding-a-locale

Watch · 1:30 Catching up a language The Manager’s bulk actions for a language that fell behind — AI Translate Pending for one locale, then for the whole project. On the page: /learn/concepts/adding-a-locale

Watch · 1:38 Translating a content block A <Translate> region as one block in the Manager: the original beside the untranslated Italian, AI Translate filling its segments, a segment reworded by hand, and the <DontTranslate> sentence held back. On the page: /learn/concepts/token-discovery

Watch · 1:30 API keys in production A key after it ships: the Activity page with a real week of reads, pausing a key without deleting it, and rotation on camera. On the page: /learn/concepts/keys-and-environments

Watch · 1:48 One organization, many projects The organization as the thing every project starts from: default locales, AI Translator and Billing settings, and a project switched back to inheriting them. On the page: /learn/dashboard

Watch · 2:22 Usage & credits The two meters and how a project gets funded: API usage against the plan, prepaid and free credits, a transfer to a project, and its monthly limit and auto recharge. On the page: /learn/dashboard

Watch · 1:26 Plans & payments A tour of what is on file: the plan and billing cycle, Change Plan, Payment Methods, Addresses and Invoices — every dialog cancelled. On the page: /learn/dashboard

Watch · 1:13 Notifications The inbox and its filters, then account defaults by in-app and email, with a per-project override turned on and off again. On the page: /learn/dashboard

Watch · 1:47 Connect your AI assistant Langsys inside an AI assistant over the hosted MCP server: claude mcp add, the Authorize Access screen, a real answer about the Store’s languages, and the connection revoked from Security. On the page: /learn/dashboard

The cuts are rendered from the langsys-demo-videos masters and published in the langsys-demos repo — the same demo apps every SDK page opens in StackBlitz.