CoverSentry

CoverSentry is an AI checker tool. Free cover letter AI detector that scores a letter as human, mixed or AI, flags likely chatbot phrasing, and suggests edits. Upload a PDF, DOCX, RTF or TXT file or paste text, no signup required, with files processed in memory and discarded.

CoverSentry is a free web tool that scans a cover letter for signs of machine generation. The premise is simple: recruiters and hiring managers increasingly screen for text that reads like it came from a chatbot, so candidates who used AI to draft or polish a letter can test it before sending. The tool returns one of three verdicts (human-written, mixed, or AI-generated) along with a detection probability and a short set of recommendations for tightening the text. The workflow is deliberately short. A letter can be uploaded as PDF, DOCX, RTF or TXT up to 50MB, or pasted directly into a text box with a 10,000 character ceiling and a 200 character minimum. Behind the scenes a fine-tuned BERT model, trained on a custom corpus of cover letters, looks for phrasing patterns that separate machine output from human writing. Results appear immediately, and the site states that letters are analyzed in memory and discarded rather than stored, with no cookies used for tracking. It suits job seekers who drafted with ChatGPT or a similar assistant and want a second opinion before applying, plus career coaches reviewing client documents at volume. The site is candid about the limits of the approach: an October 2026 note says newer frontier models such as Opus 5.5, Sol 6 and Astra now write convincingly enough that the detector cannot reliably flag them, and retraining would raise false positives. Within the broader detector market, CoverSentry is narrower than general purpose AI text checkers because it targets one document type, but it pairs the scan with a free CV builder (bullet points for 1,200+ job titles, PDF and DOCX export, no watermarks) and a resume examples library. Detection is English-only.