What is Stemmy?
Stemmy is a free English vocabulary app for Chrome. It is built around one idea: the best time to learn a word is the moment you encounter it in real reading. So instead of making you open a dictionary or switch apps, Stemmy sits inside the browser and shows you the meaning that fits the sentence you are on when you highlight a word, click the Stemmy button beside it or press Alt+Shift+D.
You can then save that word to your Vocabulary Wallet, explore its root words and etymology with WordDNA, and bring it back later through short Review sessions that use spaced repetition. Free to install. No paid plan is offered today. AI features need a free account (Google Sign-In or email). Each account gets 150 free AI uses in total, once; Ghost Card lookups and cloud voice draw on them.
How Stemmy works: a step-by-step walkthrough
- Install. Add Stemmy to Chrome from the Chrome Web Store. It is free to install. For AI meanings, create a free account with Google Sign-In or email; it comes with 150 free AI uses.
- Select a word. While reading, highlight a word you want to understand better and click the Stemmy button beside it, or press Alt+Shift+D. The Ghost Card appears beside the text — no tab switching.
- Read the meaning in context. You see the meaning that fits your sentence, the word's roots (WordDNA) and its pronunciation.
- Save to Vocabulary Wallet. Save it. The word, its meaning, the source sentence and the page link are stored in your browser. Search them, grouped into categories, in the side panel or the dashboard.
- Meet the word again. Use AI Stories (short passages written from the words in your review queue) or Immersion (your saved words appear again on pages you read) to meet saved vocabulary in fresh contexts. Both are AI features and need your free account.
- Review and recall. When a word is due for practice, it appears in your Review session. Choose how well you remembered it (Again / Hard / Good / Easy) and the algorithm adjusts when you will see it next.
Core features
Contextual definitions
Stemmy reads the surrounding sentence and writes the meaning that fits that specific use of the word. Ghost Card lookups draw on your 150 free AI uses. This is the primary difference from a standard dictionary extension, which returns a static list of all possible senses and leaves you to pick the right one.
WordDNA — root words and etymology
Next to the meaning, WordDNA shows the word's roots. For example, resilient breaks into the Latin re- (back) + salire (to jump). Understanding the root connects this word to others in the same family and makes the meaning easier to remember.
Vocabulary Wallet
Your Vocabulary Wallet is the collection of words you have saved. Each entry keeps the word, its meaning, the source sentence and the page link. The Wallet is stored in your browser (chrome.storage.local). Search your words, grouped into categories, in the side panel or the dashboard, and export or import the whole wallet as JSON.
Spaced-repetition Reviews
Reviews are short flashcard sessions that cover only the words that are due. Stemmy shows you a saved word and asks whether you can recall its meaning. You rate it Again, Hard, Good or Easy, and spaced repetition (FSRS) schedules the next review. Sessions can be paused and resumed.
AI Stories and Vocab Immersion
AI Stories writes short passages from the words in your review queue, so each word appears in a fresh context. Immersion, which is optional, shows your saved words again on pages you read, with one click back to the original text. Both are AI features and need a free account.
X-Ray
X-Ray scans a difficult page and shows which words are worth learning. Instead of saving everything, you choose deliberately from a shortlist. This keeps your Vocabulary Wallet focused.
Who Stemmy is for
- Intermediate to advanced English learners who read English articles, books, or content online and want to close vocabulary gaps without interrupting their flow
- Non-native professionals working in English who encounter specialist vocabulary in reports, emails, and documents
- Native speakers building specialist vocabulary in science, law, finance, technology, or any field with dense jargon
- Students reading academic texts in English who need precise definitions and etymology
Stemmy vs other vocabulary tools
| Feature | Stemmy | Plain dictionary extension | Anki |
|---|---|---|---|
| Works while reading | ✓ | ✓ | ✗ |
| Meaning that fits the sentence | ✓ (free account) | ✗ | ✗ |
| Saves the sentence and page link | ✓ | ✗ | Manual |
| Spaced-repetition review | ✓ | ✗ | ✓ |
| Root words | ✓ (WordDNA) | Sometimes | ✗ |
| Price | Free to install; no paid plan today | Varies | Varies |
Frequently asked questions
What is Stemmy?
Stemmy is a free English vocabulary app for Chrome. It shows what a word means in the sentence you are reading, saves it to a Vocabulary Wallet in your browser with its sentence and page link, shows its roots with WordDNA, and brings it back through spaced-repetition Reviews.
Is Stemmy free?
Yes. Free to install. No paid plan is offered today. AI features need a free account (Google Sign-In or email). Each account gets 150 free AI uses in total, once; Ghost Card lookups and cloud voice draw on them.
How is Stemmy different from a dictionary extension?
A dictionary extension gives you a list of definitions. Stemmy gives you the one definition that fits the sentence you are reading, adds etymology via WordDNA, saves the word with its sentence, and then schedules review sessions so you actually remember it. The difference is between looking a word up and learning it.
Does Stemmy work on any website?
Stemmy works on the web pages you read in Chrome, such as news sites, articles and documentation. It does not work on Chrome's own internal pages (chrome://) or browser-level PDF viewers.
What is the Vocabulary Wallet?
The Vocabulary Wallet is Stemmy's word storage. Each word you save keeps its meaning, the source sentence and the page link. The Wallet is stored in your browser; you can search it by word or category, export it as JSON, and sync it across signed-in Chrome browsers if you switch sync on.