Transparency disclaimer up front: I am the creator of ZapVox. This comparison is biased by definition — but I commit to one rule: about Kaption AI, I only state what is public on their official page and on the Chrome Web Store. No invented limitations.
If you're choosing an extension to transcribe WhatsApp Web voice messages, these are probably the two options on your list. Let's get to it.
Before the two of them, a reminder: WhatsApp itself has native transcription, but according to its official FAQ, on WhatsApp Web it has rolled out only to some devices, and when it shows up it handles one voice note at a time. I covered the details in Does WhatsApp Web transcribe audio?.
The 30-second summary
- Kaption AI leads the category in installs: 50,000 users and a 4.8 rating (4.9K reviews) on the Chrome Web Store as of September 24, 2026. If you want the most popular option, that's the one. Its list of advertised features is long: automatic transcription even in chats you haven't opened, summaries, translation into 90+ languages, search, chat export (HTML/CSV), scheduling, reminders, MCP integration, and desktop and mobile apps.
- ZapVox competes on published pricing in Brazilian reais (Starter R$14.90/month, Pro R$29.90 /month) with a 7-day trial and no card, on reach (99+ languages), on features Kaption doesn't advertise (per-contact notes, transcribing your own voice notes, your own AI key, custom glossary, daily digest, scheduling files, a separate rule for groups) and on locality: built in Brazil, Portuguese support, built under Brazil’s LGPD from day one.
Comparison table
| Criteria | ZapVox | Kaption AI |
|---|---|---|
| WhatsApp Web audio transcription | ✅ Automatic for new voice notes in the open chat (can be turned off) + ✍️ button on any voice note | ✅ Automatic, even in chats you haven't opened (advertised) |
| Transcribing your own voice notes | ✅ Yes, optional, just for reading | Not stated |
| Users and rating (Chrome Web Store) | Smaller base, growing | 50,000 users; 4.8 rating (4.9K reviews) |
| Pricing | Starter R$14.90/month; Pro R$29.90/month or R$229.90 /year, in BRL | Basic and Pro plans; prices not published |
| Free tier and no-card trial | ✅ 8 transcriptions/day, no card + 7-day trial, no card | Free to install, no card; limits not published |
| Languages | ✅ Transcription in 99+ languages (Whisper) | Language chosen per chat (36); translation into 90+ |
| Translation & summaries | ✅ Translation; voice note and full-chat summaries (Starter, Pro and trial) | ✅ Advertised (including translating your reply as you type) |
| Search across transcribed audios | ✅ Yes (last 90 days on paid plans) | ✅ Advertised |
| Export | ✅ Transcripts as TXT (Starter and Pro) | ✅ Chat as HTML (with media) or CSV; contacts and group members |
| Message scheduling | ✅ Messages and files (3/day on Free), recurrence + variables | ✅ Advertised, with repeat |
| Reminders | ✅ Yes, a notification just for you | ✅ Advertised |
| Per-contact notes | ✅ Yes | Not stated for the extension |
| Per-chat and group settings | ✅ ⚙️ per chat; separate rule for groups | Language and notification sound per chat |
| Custom glossary (technical terms, proper names) | ✅ Yes (Pro) | Not advertised on the official page |
| Daily audio digest | ✅ Yes | Not advertised on the official page |
| Bring your own API key (BYOK) | ✅ Groq (free) or OpenAI | Not advertised on the official page |
| MCP integration and desktop/mobile apps | No; it's a browser extension for your computer | ✅ Advertised |
| Browsers | Chrome, Edge and Firefox | Chrome, Edge and Firefox |
| Privacy | Audio goes to a cloud transcription service and is not stored by us; the policy cites Brazil's LGPD; Portuguese support | Says audio is sent for processing and discarded; the policy cites European and Californian privacy laws; LGPD not stated |
Sources: Kaption's Chrome Web Store listing, Kaption's website and privacy policy, and ZapVox's own pages, checked on September 24, 2026. "Not stated" means the official source doesn't mention the feature, not that it doesn't exist. If something changed, email [email protected] and I'll fix it.
Where Kaption AI wins
Honesty requires it: traction and social proof. 50,000 users and a 4.8 rating from 4.9K reviews on the Chrome Web Store — a validated user base that ZapVox doesn't have yet. And it's not just size. Kaption advertises features ZapVox doesn't have, or doesn't offer the same way:
- automatic transcription even in chats you haven't opened;
- exporting the whole chat as HTML (with playable audio and media) or CSV, plus contacts and group members;
- translating your reply as you type, across 90+ languages;
- MCP integration with ChatGPT, Claude and Cursor;
- desktop and mobile apps, and an interface in 31 languages.
For pure audio transcription, it's a mature, well-rated product — I won't pretend otherwise.
Where ZapVox wins
1. Published pricing in BRL, with a no-card trial
Starter at R$14.90/month; Pro at R$29.90/month or R$229.90/year (about R$19.16/month). The prices are on the plans page, in reais, and you can try it for 7 days with no card. Kaption mentions Basic and Pro plans but doesn't publish prices or currency on its website or on the Chrome Web Store (I checked on September 24, 2026). So there's no price comparison to make here; what I can say is that ZapVox's price is out in the open. For anyone earning in reais, predictability matters.
2. Beyond transcription: search and daily digest
Transcribing is just the start. ZapVox keeps the last 90 days of transcriptions searchable — "which audio had the client's address in it?" becomes a 2-second search. The daily digest compiles everything that arrived as audio during your day, so you don't reopen 14 chats.
3. Custom glossary
Every generic transcriber trips on technical terms: medication names, legal jargon, internal company acronyms. In ZapVox Pro you register your terms in the glossary and transcriptions start respecting them. For doctors, lawyers and sales teams, that moves accuracy from "good" to "usable in records".
4. Message scheduling done responsibly
ZapVox schedules individual messages (text or files) to a specific contact, with recurrence and variables like {{name}} and {{date}}. It is not a bulk-sending tool — it has built-in anti-block limits (per-hour and per-day caps, time jitter, typing simulation). Prefer not to auto-send anything? Set a reminder: a notification just for you. See the full how to schedule WhatsApp messages guide.
5. A real free tier + BYOK
8 transcriptions per day with no credit card, and a 7-day trial of the paid plans, also with no card. If you want volume without paying for a plan, you can plug in your own Groq or OpenAI key (BYOK): your key's quota applies instead of the ZapVox daily limit — tutorial here on the blog.
6. LGPD and Portuguese support
Brazilian company, privacy policy designed around LGPD (audios discarded after processing, API keys encrypted locally) and support that replies in Portuguese — no machine translation.
7. Per-contact notes, your own voice notes and a rule for groups
Three things Kaption doesn't advertise. A pinned note per contact, to keep what you agreed last time or an order detail. The option to transcribe the voice notes you sent yourself, so you can reread what you said. And per-chat settings in ⚙️, with a separate rule for groups: you can keep automatic transcription on in a client's chat and off in the family group.
Verdict: which one to choose?
- Choose Kaption AI if you want the most-installed option in the category, automatic transcription even in chats you haven't opened, chat export as HTML or CSV, MCP integration or a mobile app.
- Choose ZapVox if you want published pricing in BRL and a no-card trial, need accuracy on technical terms (glossary), want to find information later (audio search + daily digest), rely on per-contact notes, want to transcribe your own voice notes or use your own AI key, or value Portuguese support and LGPD compliance.
Best-case scenario: both have free versions. Test both in your real workflow for a week and see which one gives you more time back.
8 transcriptions per day on the Free plan — no credit card required.
Frequently asked questions
What is the main difference between ZapVox and Kaption AI?
Both transcribe WhatsApp Web voice messages. Kaption AI is the most-installed option in the category: 50,000 users and a 4.8 rating (4.9K reviews) on the Chrome Web Store as of September 24, 2026, with a long list of advertised features such as automatic transcription even in unopened chats, chat export, MCP integration, and desktop and mobile apps. ZapVox stands out for published pricing in Brazilian reais with a 7-day no-card trial, per-contact notes, transcribing your own voice notes, using your own AI key (BYOK), a custom glossary, a daily digest, a separate rule for groups, scheduling files, and a privacy policy that cites Brazil's LGPD.
Do both transcribe automatically, without a click?
Yes, with different reach. Kaption says it transcribes new voice notes even in chats you haven't opened. ZapVox transcribes new voice notes in the open chat on its own (you can turn this off), puts a ✍️ button on any voice note, and can also transcribe your own voice notes, just for reading.
Does ZapVox have a free plan?
Yes. ZapVox Free includes 8 cloud transcriptions per day with no credit card, and the paid plans come with a 7-day trial, also with no card. You can also use your own API key (Groq or OpenAI): your key's quota then applies instead of the ZapVox daily limit.
How much does ZapVox cost? And Kaption?
ZapVox Starter costs R$14.90 per month and Pro costs R$29.90 per month or R$229.90 per year, billed in Brazilian reais. Pro includes 150 daily operations of each type (transcription, translation, summary), custom glossary, audio search, daily digest and message scheduling. Kaption mentions Basic and Pro plans but did not publish prices on its website or the Chrome Web Store as of September 24, 2026.
Do both extensions offer message scheduling and reminders?
Yes. As of September 24, 2026, both advertise message scheduling and reminders; Kaption's scheduling includes repeat. ZapVox schedules messages and files to a specific contact, with recurrence, variables like {{name}} and {{date}}, and built-in anti-block safety limits. ZapVox reminders are a notification just for you.
Found outdated information about either product? Email [email protected] and we'll fix it fast.