---
title: "Giovanni Sizino Ennes (@vantagelabs) | Hashnode"
description: "Founder of AimVantage — AI job prep in 90 seconds. Read the latest articles by Giovanni Sizino Ennes on Hashnode."
url: "https://hashnode.com/@vantagelabs"
---

@vantagelabs

# Giovanni Sizino Ennes

@vantagelabs · London, UK · Joined April 2026

Founder of AimVantage — AI job prep in 90 seconds.

[Website](https://aimvantage.uk/)

### [The bug that killed every signup for 4 days](https://vantage-labs.hashnode.dev/the-bug-that-killed-every-signup-for-four-days?utm_source=hashnode&utm_medium=feed)

A hidden plan-picker step in my signup flow was making users pick a paid plan before they had ever seen the product. Conversion was rounding to zero. Removing it tripled signups in 48 hours. Real founder journal.

4 min read · [vantage-labs.hashnode.dev](https://vantage-labs.hashnode.dev/the-bug-that-killed-every-signup-for-four-days?utm_source=hashnode&utm_medium=feed)

[May 4](https://hashnode.com/posts/the-bug-that-killed-every-signup-for-four-days/69f8cff62cb16c4432f0300c)

### [I shipped a fake AggregateRating to my own site. Then I caught myself.](https://vantage-labs.hashnode.dev/i-shipped-fake-review-schema-then-caught-myself?utm_source=hashnode&utm_medium=feed)

A confession about SEO temptation, fabricated review schema, and the live transparency counter I built as the actual fix. Real story from launching Vantage in May 2026.

5 min read · [vantage-labs.hashnode.dev](https://vantage-labs.hashnode.dev/i-shipped-fake-review-schema-then-caught-myself?utm_source=hashnode&utm_medium=feed)

[May 4](https://hashnode.com/posts/i-shipped-fake-review-schema-then-caught-myself/69f8cfe313556e536f79b537)

### [Hardening a free public AI tool against prompt injection in 2 hours](https://vantage-labs.hashnode.dev/hardening-a-free-ai-tool-against-prompt-injection-in-two-hours?utm_source=hashnode&utm_medium=feed)

I shipped a free public AI cover-letter roast tool. Within hours I realised it was a prompt-injection target. Here are the seven layers of defense I bolted on, what each one prevents, and which ones every public AI tool needs.

7 min read · [vantage-labs.hashnode.dev](https://vantage-labs.hashnode.dev/hardening-a-free-ai-tool-against-prompt-injection-in-two-hours?utm_source=hashnode&utm_medium=feed)

[May 4](https://hashnode.com/posts/hardening-a-free-ai-tool-against-prompt-injection-in-two-hours/69f8cfd313556e536f79b535)

### [I built an open-source MCP server that lints a CV against 5 real ATS parsers](https://vantage-labs.hashnode.dev/i-built-an-open-source-mcp-server-that-lints-a-cv-against-5-real-ats-parsers?utm_source=hashnode&utm_medium=feed)

Most "ATS scanners" online give you a 0-100 score that's invented. After talking to recruiters at three companies on different ATS platforms, I confirmed: there is no real ATS score. Different parsers

3 min read · [vantage-labs.hashnode.dev](https://vantage-labs.hashnode.dev/i-built-an-open-source-mcp-server-that-lints-a-cv-against-5-real-ats-parsers?utm_source=hashnode&utm_medium=feed)

[Apr 28](https://hashnode.com/posts/i-built-an-open-source-mcp-server-that-lints-a-cv-against-5-real-ats-parsers/69f0efe010a70b3335e29641)