Some of Substack’s Biggest Newsletters Rely on AI Writing Tools
A new analysis of Substack’s top newsletters estimated that around 10 percent publish AI-generated or AI-assisted content.
Pangram Labs AI Detection
This performed the best when I tested it with a 600-word segment with a mix of human and AI-written marketing copy on 9/15/2025. Result said 2/3 AI content which was failrly accurate. However, it marked a large segment as NOT having AI-written text which was false.
SynthID - Beta (as of 9/17/2025)
Google's tool announced May 2025 to identify and watermark any kind of AI-generated content
Free AI Detector | GPT-4, GPT-3, & ChatGPT AI Checker
This performed ok when I tested it with a 600-word segment with a mix of human and AI-written marketing copy on 9/15/2025. Result said 7% AI content which was low (probably a little over 50%)
Originality AI Plagiarism and Fact Checker - Publish With Integrity
Can be used to detect AI writing. This performed almost as well as Pangram when I tested it with a 600-word segment with a mix of human and AI-written marketing copy on 9/15/2025. Result said 63% confident it was original (it was roughly 50% original). However, the color coding of the text was confusing as it did not show accurrately what was human-written and what was AI written.
Copyscape Plagiarism Checker - Duplicate Content Detection Software
This performed the worst when I tested it with a 600-word segment with a mix of human and AI-written marketing copy on 9/15/2025. Came back with "no result".
5 Reasons Why Plagiarism Detection Goes Wrong
Performing a plagiarism check is both important and difficult. Here are five common mistakes people make when checking for plagiarism.