NextLang documentation

Overview

NextLang turns a prompt, a word list, a photo or a PDF into a finished flashcard deck for the app you already study in. Generating a deck costs one credit. Everything you do with that deck afterwards is free.

20

Languages, in both directions

4

Study apps supported

5

Free credits every 30 days

43

Free phrase packs

Any pair of these works, in either direction: Arabic, Bengali (Bangla), Chinese, Dutch, English, French, German, Hindi, Indonesian, Italian, Japanese, Korean, Polish, Portuguese, Russian, Spanish, Turkish, Ukrainian, Urdu, Vietnamese.

Each part of the product has its own page.

/all-in-one

One form with a platform picker in front of it, so your text carries across platforms.

/generators

The four single-platform generators, with what each one outputs.

/user/vocabulary

Saved words grouped into dictionaries, plus spaced-repetition study and import from a long text.

/decks

Public gallery of decks other learners chose to publish.

/hub

Free situational phrasebooks, no account needed.

/tools

Free browser-side converters: CSV, text, Excel or a Quizlet export into Anki, and CSV or an .apkg into Mochi. No account, no deck uploaded. Add Audio to Anki also lives here, voicing a deck you already have for a credit per batch.

/how-to

Long-form guides for each platform and study method.

/pricing

Credit packages and what a purchase unlocks.

/user

Your credit balance, preferences and a summary of your decks.

/user/results

Every deck you have generated, by platform.

Quick start

Everything runs in the browser. You need a Google account and nothing else.

1. 01Sign in with Google. Your account gets 5 credits, and they refill to 5 every 30 days.
2. 02Open /all-in-one to pick a platform without losing your text when you switch, or go straight to a single generator from /generators.
3. 03Choose the source and target language, then describe what you want to learn, or upload a photo or a PDF instead.
4. 04Set the card count and any platform options, such as Anki fields or a CSV separator.
5. 05Generate. One credit is spent per generation, whichever generator you used.
6. 06Download the deck in your app format, or keep it here: single words go to your vocabulary from any card, and the whole set goes in one tap with Save all, on a spaced-repetition schedule.

Generators

Four generators write decks in each platform's own import format, so nothing needs column-wrangling on your side.

/all-in-one drives the same pipeline from a single form: generate for one platform, then switch the picker and generate again without retyping the source. Each generation costs its own credit. These options apply across the generators.

Card count

5 to 15 cards on the free tier, up to 30 once you have bought credits.

Photo input

Upload a JPG, PNG or WebP up to 3MB instead of writing a prompt. Drag it onto the field, paste it straight from your clipboard with Cmd+V or Ctrl+V, or browse for a file. Works in every generator, including all-in-one.

PDF input

Upload a PDF up to 10MB and 30 pages: a textbook chapter, a handout, a scan or a photo saved as PDF. There is no OCR step to run, because the model reads both the text layer and a rendered view of every page. A file that is too large, too long, corrupted or password-protected is refused before a credit is spent.

Anki fields and tags

Choose which fields each note carries and which tags it gets. Both survive into the .apkg as real Anki fields and tags.

Separators and quoting

Pick comma, semicolon, tab or pipe for text exports, and decide whether values are quoted.

Markdown delimiter

Mochi markdown output uses === between cards by default, and you can set your own.

Saved preferences

Languages, formats and separators are remembered, so the next generation starts where you left off.

Your saved decks

Everything you generate stays in your account. A deck can be re-downloaded, grown, studied, published or deleted long after the credit was spent.

History per platform

Every set you generate is saved to your account and listed by platform, so a deck you made weeks ago is still one click away.

Re-download for free

Export any past set again, in any format it supports, without spending another credit. Downloading files needs a past credit purchase, but not a new one each time.

Growing a saved deck

A deck is not final once it is generated. Open it and add more cards from its own page: decks grow in steps of up to 30 cards (15 on the free tier), to a ceiling of 200 cards, one credit per step. The cards already in the deck are excluded from the request, so you get new material rather than duplicates, and the deck keeps the format, separator, fields and tags you first chose. Cloze decks, decks built from a file and decks published to the gallery cannot be grown this way yet.

Editing in place

With premium you can reopen a saved deck and change its title, prompt or card content, without regenerating it.

Study, publish, delete

Run any past set through study mode, publish it to the gallery or unpublish it again, and delete what you no longer need.

AI models

Cards are written by OpenAI's current models, picked per request. You never choose one, and the choice never changes what a generation costs.

Structured output

Every generation asks the model for a strict JSON shape rather than prose, so cards arrive as data with the fields already separated. That is why an export imports cleanly instead of needing cleanup.

Routing you do not configure

The right model is chosen from what you gave it: text, an image, a PDF, and whether English is one of your two languages. There is no model picker, and no generation costs more than one credit.

Short results are refunded

If a generation comes back with fewer cards than you asked for, the credit is returned and you keep the cards that were made. If nothing usable comes back at all, the credit is returned and nothing is saved.

Your material is read, not obeyed

Text, images and PDFs are passed to the model as material to learn from. Instructions written inside a document are ignored, so a PDF cannot talk the generator into doing something else.

Levels are part of the prompt

Your CEFR choice, card count, languages and format options are written into the request itself, which is why an A2 deck and a C1 deck from the same topic contain different words.

Study mode

A generated set is studyable on the spot, as a proper flip-card deck. Nothing has to be downloaded or imported first.

Flip cards, not a list

One card at a time, front then back. Every result page has a study view, and so does every deck in the gallery, so a set can be reviewed the second it exists.

Rate as you go

Mark a card Got it or Still learning. Cards you are still learning come back in the same session, which ends with a summary once every card has been rated.

Shuffle and restart

Reshuffle the deck or start over at any time, with a warning before real progress is cleared. You can also study the set reversed, translation first.

Focus mode and keyboard

F fills the screen and hides everything else. Space or Enter flips, left and right move, up marks Got it, down marks Still learning, A plays the pronunciation, S saves the word to your vocabulary, Esc leaves.

Saving while you study

Any card can go into your vocabulary from its face, and Save all takes the whole set at once. From there the spaced-repetition schedule takes over.

No import needed

Study mode costs nothing and needs no download. Animations respect a reduced-motion preference.

Vocabulary and spaced repetition

Words you save, one at a time or in bulk from a text you paste, are yours to review here, on a Leitner schedule that decides what comes back and when.

Saving words

Add a word from a result you just generated, from a study session, from a gallery deck, or by hand. Each entry holds a term, its translation and an optional example sentence.

Import from text

Paste an article or transcript, or upload a .txt, .md, .srt, .vtt, .sbv, .ass, .ssa file of up to 2 MB, and get back the words in it worth learning at your CEFR level, each with a translation and an example sentence taken from the text. Up to 60,000 characters per run.

What the import costs

One credit per extraction, up to 50 words at a time on the free tier and 150 once you have bought credits. The credit comes back if nothing usable is found. Picking which of the results to keep is free, and words already in the dictionary are skipped.

Dictionaries

Words are grouped by language pair, so Spanish to English and English to Japanese stay separate. You can keep up to 5,000 saved words.

Export a dictionary as a deck

Export deck turns the words on screen into an Anki .apkg or a Mochi .mochi, with the pronunciation audio embedded. Search and the Learning or Learned filter narrow what goes in, so a subtitle import can leave as a deck without a second generation. File exports need purchased credits, the export itself costs none.

Save a whole generated set

Save all, in the study view of a result page, adds every card in the set to the dictionary for that pair. Words already saved are skipped, and the rest land due for review straight away. Cloze sets stay out of this, since a sentence with a blank is not a word.

Leitner scheduling

Five boxes with 1, 3, 7 and 21-day intervals. Got it moves a word up one box, Still learning sends it back to the first box and makes it due again the same day. Reaching the top box marks the word learned.

Sessions

A session serves up to 20 words that are due, longest overdue first, then offers to study the next portion. Learned words come back every 21 days for maintenance.

Review all

Free practice over a whole dictionary, ignoring what is due. Ratings still feed the schedule.

Direction and focus

Study term to translation or flip it. Focus mode goes fullscreen, with arrow keys to move, space to flip, F for focus and Esc to leave.

Manual overrides

Mark one word or a whole dictionary as learned at any point, and unmark it just as easily.

Card types

Word pairs are the default. For Anki and Mochi you can switch to cloze: fill-in-the-blank sentences that hide one word.

Basic cards

The default: the word on the front, its translation on the back, plus any extra fields you picked.

Cloze cards

Anki and Mochi can be generated as fill-in-the-blank sentences instead: one natural sentence in the language you are learning with a single word hidden, and the full translation underneath.

Native in both apps

Cloze decks import as Anki's own Cloze note type and Mochi's own hidden-text syntax, so the blank works inside those apps, not just on the site.

Audio included

The speaker on a cloze card reads the whole sentence, and the same audio travels inside the exported package.

Pronunciation audio

A card that speaks teaches you to recognize the word, not just read it. Tap the speaker on any card to hear the word in the language you are learning.

Where it plays

A speaker button sits on cards in study mode, on the card grids of result pages, on published decks in the gallery, and next to every saved word in your vocabulary. It pronounces the side in the language you are learning. Gallery playback needs you to be signed in, and cloze decks stay silent there so the audio does not read out the hidden word.

Natural voices

Neural text-to-speech voices cover all supported languages. Every word is synthesized once and then served instantly for everyone from a shared cache.

Audio inside .apkg

Anki exports embed the mp3 files, so the deck keeps speaking inside Anki Desktop, AnkiDroid and AnkiMobile. If audio is momentarily unavailable, the deck still exports, just without sound.

Gallery downloads

Decks published to the gallery export with sound too: the .apkg and .mochi you download from a deck page carry the same embedded audio, with an 'Include audio' toggle next to the download buttons. You need to be signed in, since the audio is synthesized per request.

Voicing a deck you already have

The Add Audio to Anki tool at /tools/add-audio-to-anki takes any .apkg, voices the field you choose, and hands the deck back with the recordings inside. One credit covers 200 cards, and a leftover smaller than half a batch is free.

Free and premium

Word pronunciation is included for everyone, free tier included. Example-sentence audio, in the vocabulary and in exports, is a premium extra.

Deck gallery

A public library of decks that NextLang users generated and chose to publish. Free to browse, with no account and no credits.

Browsing

The gallery is free and open, with filters by platform and language pair. Decks are user-generated and not reviewed by us, so check anything you plan to memorise.

Publishing

Open one of your results and turn on Publish to gallery. Publishing needs a past credit purchase, a descriptive title and at least 10 cards. You can keep 15 decks published at once: unpublish one to make room for another. The gallery has a My decks filter so you can see your own published decks in one place.

On a deck page

Every card is a flip card. Download the deck as .apkg or .mochi, copy it as tab-separated text for Quizlet or a spreadsheet, or save single words to your vocabulary.

Privacy

Every deck is private until you publish it. Deck pages show no author name, published decks are not indexed by search engines (only the decks our team curates are), and unpublishing takes the page down immediately.

Phrasebooks

Hand-vetted phrase packs for the situations textbooks skip. 43 scenarios are live across 8 language pairs.

What is in a pack

Phrases with their translation, usage notes, and a reading line where the script needs one. Where politeness or pronouns depend on it, the pack states who is speaking to whom, and a line that belongs to one region carries a small tag. Every pack also lists the false friends that trip up that specific language pair.

Language pairs

Russian to Polish, Spanish to English, French to English, English to Japanese, English to Vietnamese, English to Portuguese, English to Italian, English to German.

Scenarios

Doctor visits, government offices, renting, school, banking, job interviews, trains, restaurants, markets and more. Every pack listed is readable today.

Save a pack

One tap saves every phrase in the pack to My Vocabulary, in the pair's own direction, where it joins study mode, spaced repetition and export. This is the only part that asks you to sign in.

Cost

Reading is free and fully open: no account, no credits, nothing gated. Saving a pack to your vocabulary needs an account, and still costs no credits.

Converter tools

Cards you already have, in the wrong shape. The converters at /tools turn a spreadsheet, a word list or an existing deck into a file your app opens, without an account and without a credit.

Six converters

CSV, text, Excel and a Quizlet export all turn into a ready-to-open .apkg; CSV turns into a .mochi package; and an existing .apkg comes back as .mochi. They differ only in what you arrive with.

Add Audio to Anki

A seventh tool that voices a deck you already have: upload the .apkg, pick the field to pronounce and its language, and download the same deck with the mp3 files embedded. The language is detected from the deck, a preview lists the exact lines the voice will read, and the price is shown before you spend anything: one credit per 200 cards, rounded to the nearest so a small leftover is free. A large deck asks for confirmation, and one you cannot afford is refused up front rather than half voiced.

Nothing is uploaded

Parsing, packaging and downloading all happen inside the page, so your deck file never leaves your browser and no account is involved. Add Audio to Anki is the one exception: the deck still stays local, but the text of the field you asked us to voice is sent to be turned into speech.

It guesses, you correct

Drop a file and the converter works out the column separator, the card separator and whether the first row is a header, then previews the cards it found. Every guess is a dropdown you can change.

Extra columns survive

Point any column at Front, Back, Example, Notes or Tags, or leave it out. For Anki those become real note fields and tags; for Mochi, which has two sides, the extras are appended to the back as Markdown.

Limits

Files up to 5 MB and decks up to 20,000 cards, so the tab stays responsive. Converted decks carry text, not media: a .mochi built by the converter from someone else's .apkg leaves the audio behind.

Cost

The six format converters are free, with no credits and no signup, because they cost nothing to run. Add Audio to Anki is the exception, since the voices run on paid servers: reading and setting up the deck is free, and only the voicing step signs you in and spends credits.

Install as an app

NextLang installs straight from the browser as a Progressive Web App, so it sits on your home screen next to everything else. There is no native app to download, and none is needed.

Android and Chrome

Open the browser menu and choose Install app. NextLang is added as a real app with its own icon and its own entry in the launcher, not as a bookmark.

iPhone and iPad

Tap Share in Safari, then Add to Home Screen. The icon lands on your home screen and opens NextLang like any other app.

Windows, macOS and Linux

In Chrome or Edge, click the install icon at the right of the address bar. NextLang then opens in its own window, with its own entry in the dock or taskbar.

What installing gets you

The app opens in its own window, without tabs or an address bar. A long press on the icon, or a right click on desktop, jumps straight to the generator or to your vocabulary.

What it is not

There is nothing to download from the App Store or Google Play, and nothing to keep updated. There is also no offline mode yet: the installed app needs a connection, exactly like the site.

Credits and premium

One credit is spent per generation, whichever generator you use. Premium is unlocked by your first purchase and stays unlocked, even once the credits are gone.

Guides

Long-form walkthroughs for each platform, plus the reasoning behind the study methods. Some sections are premium.

Email

Transactional mail only. Nothing is sent on a schedule, and a failed send never blocks what you were doing.

Welcome

Sent once, on your first sign-in.

Purchase receipt

Sent after Stripe confirms a successful checkout.

Refund confirmation

Sent when a charge is refunded in full.

Low-credit reminder

Sent once when your balance reaches its last credit, and re-armed only after you buy more.

Getting-started tip

Sent once, a few days after signup, and only if you have never generated a deck.

Unused-credits reminder

Sent once when purchased credits sit untouched for a month, and re-armed only by a new purchase. Reminders never exceed one a week in total.

Unsubscribe

Every reminder carries a one-click unsubscribe and a standard List-Unsubscribe header. Receipts and account mail always send.

Email notifications panel

Your profile lists every email we send, switches reminders off and back on, and marks the ones that always send.

Privacy and security

What leaves your browser, what does not, and what protects the parts that cost money to run.

Analytics

Privacy-friendly Umami with no cookies, tracking a fixed list of events: sign-in, generation start and outcome, checkout, study sessions, exports, vocabulary saves, deck publishing and phrasebook views.

Your content

Prompts and generated cards are never sent to analytics. Decks stay private unless you publish them.

Uploaded files

Images and PDFs you upload are sent to OpenAI to generate the cards and stored on Cloudflare R2 behind a public URL for as long as you keep the result. Deleting the result deletes the file with it, and deleting your account removes all of them.

Cookie consent

Analytics load only after you accept the banner, and tracking is a no-op until then. You can withdraw consent from the footer at any time.

Input handling

Every prompt and field is sanitized and validated on the server before it reaches the model.

Rate limiting

Per-account limits sit in front of generation, sign-in and every paid path, so one account cannot be used to run up someone else's bill.

Payments

Checkout runs on Stripe and card details never touch NextLang. Credits are added only after Stripe confirms the payment, and a refunded charge is handled the same way.

Support