Quick Answer
ChatGPT Voice is a general voice assistant. You can ask it to play an interviewer, and its Live mode lets you interrupt and talk naturally. Free accounts get limited Live access and Go and Plus get 3 hours per rolling 24 hours, according to OpenAI's help centre in November 2026. It is not an interview product: it does not know your round unless you set it up, its transcripts are not word for word, and it cannot reliably judge a technical answer. Mockly English is live 1:1 practice with UK data engineers who run the round and correct your English line by line, at $50 a session after a free 30-minute trial. Use ChatGPT for daily reps and Mockly for judgement. You can even book a Mockly coach from inside ChatGPT.
What makes Mockly English different
Mockly English is built for one job: getting non-native engineers and data professionals through tech interviews, and through meetings, in English. Your coach is a practising UK data engineer who also teaches English. They run the real round (coding, system design, SQL and data, behavioural, HR), then correct your English line by line and have you say it again. The first 30 minutes are free with no card; after that it is $50 a session, with no subscription.
⚡ Quick Stats
What ChatGPT Voice Does
These facts come from OpenAI's ChatGPT Voice help article, checked on 10 November 2026.
- You speak and ChatGPT speaks back, inside a normal chat, so you can read the text and scroll back.
- There are three voice options: Live (listens and speaks at the same time, so you can interrupt), Advanced (the previous real-time voice, with video and screen sharing on mobile) and Standard (turn by turn).
- Live usage is measured over a rolling 24 hours: limited on Free, 3 hours on Go and Plus, 15 hours on the $100 Pro plan and unlimited on the $200 Pro plan (subject to abuse guardrails).
- You can ask Live to wait until you are ready, which helps when you want to think before answering. Long pauses can still make it respond.
- OpenAI says voice transcripts are not verbatim records and may not match exactly what was said.
- Audio clips from Live and Advanced conversations are stored with the chat and kept for 30 days.
A Prompt That Makes ChatGPT a Better Mock Interviewer
Out of the box, ChatGPT is polite and encouraging. For interview practice you want the opposite. Paste this into a chat, then start Voice:
You are interviewing me for a [mid-level backend engineer] role at a UK company. This is a 30-minute behavioural screen.
Ask one question at a time. Wait until I say "done" before you respond.
After each answer, ask one follow-up question about the weakest part of my answer.
Do not praise me. After every second question, list: (1) any phrase that sounded unnatural or changed my meaning, with a better version; (2) any place I said "we" when I should say "I".
Then ask me to say my last answer again.
This gets you closer to a real round. It still cannot tell you how a UK or US interviewer would score you, and it may miss mistakes because the transcript is not word for word.
Where ChatGPT Falls Short for Tech Interviews
- Technical judgement. It will discuss your system design fluently, but it can agree with a design that would not hold up. An engineer pushes on the weak point.
- Exact corrections. If the transcript smooths over what you actually said, the feedback is about a cleaner version of your answer than the one you gave.
- Pressure. It is easy to stop, restart or ask for a hint. That is good for learning and bad for rehearsing the real thing.
- Calibration. It does not know what “good” looks like for a mid-level data engineer at a UK company unless you tell it, and then it is guessing.
- Diagrams and code. Live does not support video or screen sharing, so it cannot follow a whiteboard while you talk.
Free Mini App
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Try the Mini AppSide by Side
| ChatGPT Voice | Mockly English | |
|---|---|---|
| What it is | General AI assistant with voice conversation | Live 1:1 tech interview English and business English coaching |
| Who you talk to | An AI model | Sophie or Tom, practising UK data engineers who also teach English |
| Interview rounds | Whatever you set up in your prompt | Coding, LeetCode, system design, SQL and data, behavioural, HR, case |
| Feedback | Only what you ask for; transcripts not verbatim | Line-by-line corrections, then you say it again; drill list after the session |
| Technical judgement | Unreliable | Yes, from engineers |
| Diagrams | Live: no video or screen sharing | Excalidraw in system design sessions |
| Price | Free with limited Live; paid plans add hours | $50 a session; packs of 5, 10 or 20; free 30-minute trial |
| Best for | Daily reps at any hour | Finding and fixing the English that costs offers |
How to Use Both
- Book Mockly's free 30-minute trial first. The coach tells you your main English habits.
- Put those habits into the ChatGPT prompt above (“flag every time I say ‘actual’ when I mean ‘current’”) and practise daily.
- Before the real loop, do one full round per round type with a Mockly coach.
Mockly English also works inside ChatGPT. Add the Mockly connector and you can see coach availability, book your free trial and check your CV or STAR stories without leaving the chat. See how to use Mockly in ChatGPT and Claude.
Mockly prices (as of November 2026)
- Mockly: a free 30-minute trial with a coach on Google Meet. No card and no subscription.
- Mockly: live 60-minute 1:1 sessions are pay-as-you-go. One session is $50; packs of 5 ($237.50), 10 ($450) or 20 ($850) cost less per session. Credits last 12 months and work with either coach.
- Mockly: Premium is the self-study course at $9.99/month, or $59.99/year, with a 7-day free trial. It does not include a coaching session and you do not need it to book one.
Verdict
ChatGPT Voice is the most flexible free practice partner, and with a strict prompt it is a decent behavioural sparring partner. It is not a substitute for an interviewer who knows the round. Use ChatGPT for volume and Mockly English to find and fix what actually costs you the offer.
Talk to an engineer-coach first
Book a free 30-minute Google Meet with Sophie or Tom. No card, no subscription. You practise a short interview-style prompt in English and leave with a plan for what to work on next.
Book a Free Trial →