MockDefense vs VivaCoach: A Free Viva Prep Alternative

How they differ and who each suits

VivaCoach was built by an Oxford PhD holder and is designed around one core idea: you upload your actual thesis, and the tool analyses it to generate questions tied to your specific content. You pick a difficulty — warm-up, standard, or hostile examiner — and work through practice sessions with model answers, Socratic follow-ups, and a personalised one-page cheat sheet at the end. The £59.99 / $79.99 one-time fee never expires and covers 5 full-length sessions. A free preview gives you 3 questions based on the first 10,000 words of your thesis, no card required. Pricing shown here was accurate at the time of writing (June 2026); check vivacoach.ai for current figures.

MockDefense is currently free during beta — full access, no card required. Instead of a single examiner, you face a committee of three: Dr. Hale (Chair, supportive but rigorous, runs the room), Dr. Reyes (Methodologist, who goes after your design, stats, and validity), and Prof. Sinclair (Outside Examiner, adversarial, challenges your contribution's novelty and significance). You cannot choose which one asks next; they rotate. You start by pasting a 2-3 minute summary of your work rather than uploading your full document. Two modes are available: a Full Mock Defense of roughly 30 exchanges across every area, and a Focused Drill of 12 questions on a single topic.

Neither tool is a substitute for a human mock with your advisor or a real committee member. Both are tools for content drilling and question fluency before that point.

The key differences, side by side

When VivaCoach is the better choice

VivaCoach is the stronger tool when you want questions drawn directly from your specific text. Because it reads your uploaded document — up to 100,000 words — it can surface questions about details in your methodology chapter, specific findings, or particular theoretical commitments that a summary-based tool would not reach. That passage-level analysis is its main differentiator.

• You want questions tied to specific content in your thesis, not just its broad shape.
• You find model answers useful — seeing a strong answer alongside the question helps you calibrate what 'good' looks like.
• The personalised one-page cheat sheet is a feature you'd actually use for last-day revision.
• You want a one-time purchase you can return to across multiple prep sessions without a recurring cost.
• You prefer to control difficulty explicitly, choosing between warm-up, standard, and hostile mode at the start of each session.

The free preview — 3 questions based on the first 10,000 words of your thesis — lets you see the question quality before paying. That is a fair way to evaluate it.

When MockDefense is the better choice

MockDefense's main advantage is the committee dynamic. UK vivas typically involve two examiners; US defenses involve a full panel. Practising against a single examiner with an adjustable difficulty setting is useful, but it doesn't expose you to the experience of different voices asking different kinds of questions in sequence — where the Methodologist's challenge about your validity comes before the Outside Examiner's challenge about your contribution's significance. The rotating committee format is closer to that experience.

• You want to practise against multiple distinct examiner voices, not a single examiner at one difficulty level.
• You would rather not upload your full unpublished thesis to an external service. Pasting a summary keeps your complete document local.
• MockDefense's stated no-training policy on session transcripts matters to you.
• Cost is a factor — MockDefense is free during beta, with no card required.
• You want quick Focused Drills on one area (12 questions on methodology, for instance) without committing to a full session.

How to choose — and why you might use both

The practical move for most candidates is to start with MockDefense. It costs nothing, requires no card, and gives you a realistic sense of where your answers are weak across all three committee voices. If, after a few sessions, you find the main gap is that questions aren't specific enough to your actual thesis text — that you're being asked about methodology in general rather than your methodology — VivaCoach's full-thesis analysis is exactly what fills that gap.

Some candidates will find the summary-based sessions sufficient and never need to go further. Others will want both: committee-format drilling from MockDefense, and document-deep questions with model answers from VivaCoach. They address different preparation needs, so using both is not redundant.

Neither replaces a human mock with your advisor or a colleague who knows your field. Both are most valuable in the weeks before that human mock, when you're building fluency on content rather than testing room dynamics.