To use AI in WhatsApp you don't need a bot, a plugin, or ChatGPT open in another tab. You need an AI keyboard: install it, set it as your Android keyboard, and from then on you can select any text you've typed in a chat, tap a prompt like "fix grammar" or "translate to Spanish", and watch the text rewrite itself in the message box. Nothing to copy, nothing to paste, no leaving the conversation.
This guide walks through the setup and the three things people actually use it for: grammar, translation, and faster replies. The steps below use Synapse AI Keyboard, but the general workflow applies to any prompt-based AI keyboard.
What an AI keyboard does inside WhatsApp
A keyboard app sits under every text field on your phone. That position is what makes it useful: the AI works wherever the cursor is, so WhatsApp doesn't need to support anything. The keyboard does the work.
With Synapse the workflow is always the same three moves:
- Type your message in the chat box (rough is fine).
- Select the text, then open the keyboard's prompt section.
- Tap a prompt. A moment later the selected text is replaced with the AI's version.
One workflow, unlimited uses, because the prompts are free-form. "Fix grammar" is a prompt. "Translate to Arabic" is a prompt. "Make this sound less angry" is a prompt. You're not limited to buttons someone else designed.
Step 1: Install and enable the keyboard
Synapse isn't on the Play Store; you install the APK directly from the website:
- Download the free APK from synapsetalk.com. It's about 32 MB and runs on Android 8 or newer.
- Open the file. Android shows a one-time "allow from this source" prompt: tap Allow, then Install. Google Play Protect still scans the app on your device, same as any install.
- Open the app. The setup appears right on the dashboard the first time you open it, and it walks you through enabling Synapse in your keyboard settings and switching to it.
- Sign up for a free account. You get 20,000 energy credits to start, which is plenty to test every feature properly.
Total time is a minute or two. After that, open WhatsApp and tap any chat box; the Synapse keyboard comes up instead of your old one. Normal typing works exactly as before and never uses credits.
If you've never switched keyboards on Android before, we have a full walkthrough for every brand in our guide to changing your keyboard on Android.
Step 2: Fix grammar before you hit send
The most common use, and the fastest to learn:
- Type your message as it comes out. Typos, missing articles, whatever.
- Select all the text (long-press, then Select all).
- Open the prompt section on the keyboard and tap your grammar prompt, or type "fix grammar and spelling".
- Wait a moment. The corrected version replaces your draft in the WhatsApp text field.
- Read it, then send.
That last step matters. The AI corrects what you wrote; it doesn't know what you meant. Ninety-nine times out of a hundred the fix is exactly right, but the one time you typed "now" and meant "not", you want your own eyes on it before it goes to your boss.
Compare this to the old routine: copy the message, switch to a grammar app or ChatGPT, paste, copy the result, switch back, paste again. Six steps became two, and you never left the chat. If grammar is your main reason for wanting this, the AI grammar checker keyboard page goes deeper on that use case.
Step 3: Translate messages without leaving the chat
Translation follows the identical pattern, just with a different prompt:
- Type your reply in the language you think in.
- Select it, open the prompt section, and run "translate to Portuguese" (or any language).
- The translation lands in the chat box. Send.
Because prompts are free text, you control the register too. "Translate to German, formal" and "translate to German like I'm texting a friend" give noticeably different output. That's the part dedicated translation apps get wrong; they translate words, not situations.
For incoming messages in a language you don't read, copy the message into your chat box, select it, and run "translate to English and keep it under the original". Read the translation, delete it, write your reply, translate that back. Clumsy on paper, quick in practice.
Synapse ships with multi-language support (English, Urdu, Arabic, and Spanish among them), and the AI prompts themselves work with any language pair you throw at them.
Step 4: Write replies faster
Grammar and translation fix text you've already written. Replies are where the AI saves you from writing at all.
The trick is to type a skeleton and let the prompt do the flesh. A few real examples:
- Type "cant come tonight, sick", select it, run "turn this into a polite apology message".
- Type the bullet points of what you want to say to a client, run "write this as a professional WhatsApp message, friendly tone".
- Paste the long paragraph someone sent you, run "summarize this in two lines" so you can reply to the actual point.
You stay in charge of the content; the AI handles the phrasing. That's the difference between this and canned auto-replies that sound like nobody.
We keep a list of 50 tested prompts for texting if you want ready-made ones for apologies, follow-ups, tricky conversations, and work messages.
Save your best prompts as custom shortcuts
Any prompt you find yourself typing twice should become a saved custom prompt. Synapse lets you store your own prompts in the prompt section, so "translate to Spanish, casual" or "rewrite as a polite payment reminder" becomes a single tap instead of typing the instruction each time.
Freelancers get the most from this. A saved "reply to this Upwork message professionally, keep my rate firm" prompt turns a ten-minute agonize-and-rewrite session into thirty seconds. There's a dedicated rundown on the AI keyboard for freelancers page.
What it costs
Straight numbers, because pricing pages love to hide them:
- Free to install, with 20,000 energy credits when you sign up.
- Credits are spent only when you run an AI prompt. Typing, swiping, and emoji cost nothing, ever.
- When credits run low, top up between $5 and $30. No auto-renewal.
- Pay with USDT crypto and you get 30% extra energy on the top-up.
- Heavy user? There's an optional subscription for people who run AI constantly, but nobody is pushed into it. Light users just top up when needed, and testing the keyboard costs nothing at all.
A note on privacy
A keyboard sees what you type, so this question deserves a direct answer: your normal typing stays on the device. The only text that leaves your phone is the text you explicitly select and send to a prompt. If you never tap a prompt on a message, that message is never uploaded anywhere.
FAQ
Does WhatsApp allow AI keyboards?
Yes. A keyboard is a normal Android input method, and WhatsApp treats Synapse like it treats Gboard or SwiftKey. There's nothing to configure inside WhatsApp itself.
Does it work in WhatsApp Business and group chats?
Yes. The keyboard works in any text field, so WhatsApp Business, groups, channels, and status captions all behave the same.
Can it make my text bold or italic?
Formatting in WhatsApp is done with symbols like *bold* and _italic_, which you can type with any keyboard. Our WhatsApp text formatting guide covers every format, and you can ask the AI to insert the symbols for you: "fix grammar and put the deadline in bold" does both jobs in one pass.
Do I need internet for the AI features?
Yes, prompts run in the cloud. Regular typing works offline like any keyboard.
Will it slow down my typing?
No. AI only runs when you invoke a prompt. The rest of the time it's a fast, normal keyboard.
Try it on your next message
The whole thing clicks in the first five minutes of real use. Download the free Synapse APK from the download section, let the dashboard setup switch your keyboard, and run "fix grammar" on the next WhatsApp message you'd normally send with a typo. The 20,000 free credits mean you can decide whether it earns a permanent spot on your phone before paying a cent.