Isgen

Isgen is a multi-language AI content detection platform: it analyzes text and reports whether it was written by a human, an AI, or both — covering output from ChatGPT, GPT-5, Claude, Gemini, DeepSeek, Llama, Mistral and open-source models. The depth is what separates it from one-score detectors: sentence-level and phrase-level analysis with color highlighting and an AI-influence score, so you can see which parts of a document trip the detector rather than getting a single percentage. Around the core it bundles plagiarism checking, grammar correction, an AI humanizer, citation generation, bulk scanning and an integrated editor — 80+ languages, 4.9 rating from 1M+ users.

Who it's for: educators checking submissions, editors verifying freelance copy, publishers policing AI-content policies, and writers clearing their own work before submission. $11-ish tiers with bulk options. The honest calibration for the entire category: detectors are probabilistic — treat results as evidence, not verdicts, and never act on a single score without reading the highlighted passages. Isgen's sentence-level output at least shows its work.