I Tried 6 AI Detectors – Here’s What Worked

There are so many AI detectors online these days. I’ve always wondered — do they work? Or are they just another internet trend? And if they do work, which one is worth using? To find out, I decided to run a simple test. I generated a short article (approximately 600 words) using Claude AI and checked it with six popular tools that people frequently discuss. Here’s the list:

• Smodin
• Grammarly
• Scribbr
• Writer
• Undetectable AI
• Sapling

One of these was the AI detector by Smodin — I’d seen it mentioned a lot, so I was curious to see how it would handle the test. Let’s see what happened and which detector did the job best.

1. Grammarly

Grammarly is well-known for its grammar checker, but I was curious to see how its AI detector works. Visually, the interface looks nice, clean and modern. But when it comes to using the AI checker, it’s not that straightforward. It took me a bit to figure out where exactly to paste the text and where the results appear. The speed isn’t great either — the check takes longer than I expected.

On the plus side, it’s free. You don’t even need an account to see the AI percentage. The limit is also pretty generous — up to 10,000 characters per check. But what about accuracy? Well, that’s where Grammarly disappointed me. I started with a super simple test: AI text generated with a basic prompt like “Write an article about birds”. Grammarly detected only 53% of it as AI-generated.

Then I made things more complicated — I asked Claude to write a more natural, human-like article: 600 words, lively tone, structured like a copywriter would write. Grammarly detected only 23% of AI content. The more natural the AI text sounded, the less Grammarly noticed it. And that’s not great if you’re looking for reliable detection.

2. Smodin

Smodin turned out to be one of the easiest tools to use. The interface is clean, clear, and very intuitive. No need to guess where to click — everything is simple and obvious.

The free plan allows you to send up to five checks per week, each with a character limit of 5,000 characters. Another nice feature — you can upload files in different formats, not just paste text. It also supports over 100 languages, which makes it convenient for users working with multilingual content.

However, most importantly, the results were significantly better than those of many other tools.

When I tested the raw AI text (just a basic prompt without any tweaks), Smodin detected 92% of it as AI-generated. When I used the optimized prompt — with clear instructions to sound more human — the result was still solid: 78% AI.

Another helpful feature — Smodin not only shows the percentage of AI-generated content versus human-written content but also highlights specific parts of the text that appear suspicious. It gives you a clear picture of where exactly AI is likely involved, which makes analysis much easier.

3. Scribbr

Scribbr offers an intuitive and user-friendly interface, ensuring seamless navigation. It supports only five languages, which might be a limitation for some users. However, when it comes to detection accuracy, Scribbr performed exceptionally well.

The raw AI text (without any optimization) was detected as 95% AI-generated. Even the optimized version, written to sound as human as possible, was still flagged as 87% AI. And the best part? Scribbr is entirely free to use. 

4. Writer

Writer is another tool with a minimal and easy-to-use interface. The free limit is pretty generous — up to 5,000 words per check. But the results were disappointing.

Both the raw AI text and the optimized AI text were predominantly identified as human-written. The simple prompt was marked as 86% human, and the optimized version was marked as 87% human. Essentially, the Writer struggles to capture AI-generated content, even when it is produced. 

5. Undetectable AI

Undetectable AI is distinct from other tools. It checks your text against multiple AI detectors at once and shows AI Detection Likelihood results from various sources.

The free limit is huge — up to 30,000 characters per check. But the downside is speed — the check takes noticeably longer than other tools. As for results? Pretty strong.

• Raw AI text: Detected as 1% human
• Optimized AI text: Also 1% human

Impressive accuracy, but be ready to wait a bit.

6. Sapling

Sapling looks clean and is easy to use, but the free version only allows checking 2,000 characters at a time — the smallest limit among all the tools I tested.

Accuracy was mixed.

• Raw AI text: Detected as 74.7% AI
• Optimized AI text: Only 0.4% AI — missed the optimized content completely.

The check also runs slower than average, so while it works okay for raw AI text, Sapling struggles when AI content is written to sound more natural.

Which AI Detector Did the Best Job?

After testing all six tools, I can say that not all AI detectors work the same way. Some tools did a great job with raw, clearly AI-generated text, but completely failed when the content was optimised to sound more human. Others missed obvious AI sections or overestimated the capabilities of human writing.

When considering accuracy across both simple and optimised AI texts, Smodin and Scribbr demonstrated the most stable and balanced results. Both tools successfully identified AI-generated content, even when the prompt was intentionally crafted to conceal it.

Undetectable AI also impressed me with its raw detection power, though it’s slower than others. Tools like Grammarly, Writer, and Sapling worked fine with introductory AI-generated text but struggled significantly when the AI content was enhanced to sound more natural.

In short, if you need a quick, precise, and reliable AI checker, especially for tricky or hybrid content, an AI detector by Smodin showed the most consistent results in my test.