Opace AI Content Checker & Detector

Free AI content checker and AI detector for ChatGPT, Claude and Gemini text, with section evidence and hidden-character checks.

Opace AI Content Checker & Detector is a free AI content checker for Chrome. Review selected text, a web article or a pasted draft for AI writing patterns, with section readings and examples from your content. Check ChatGPT, Claude, Gemini and other AI-assisted writing before deciding what needs closer attention. FREE AI CONTENT DETECTOR Check the current page after clicking the extension icon, use the selected-text context menu, or paste a draft. Run the trained model on your device after an explicit verified model-data download. Open each scored section to read the passage and separate writing observations, and jump to that passage on the captured webpage. Inspect hidden and lookalike characters separately from the AI reading. Review writing suggestions with examples. Protect names, figures, dates, quotations, citations, links and code when considering supported character-only changes. Compare original and candidate text before copying; the extension does not rewrite the page. Download branded PDF and HTML reports containing the scored passages and named checks. Export content-free JSON receipts or copy a summary without sharing your draft. Inspect JPEG, PNG, WebP or PDF files locally for C2PA Content Credentials. This checks credentials, not whether image pixels are AI-generated, and does not extract PDF text for AI analysis. HOW TO CHECK A PAGE OR DRAFT Open an ordinary webpage, click the Opace extension icon and choose This page. For an extract, select text and choose the Opace context-menu action. For a private draft, choose Paste. Select On this device for model analysis or Quick checks only for character and writing-rule checks. Expand a section for evidence, then save a report. Use Back to report or the available steps at the top to revisit results. PRIVACY AND PERMISSIONS Analysis runs on your device. The optional EU analysis route is unavailable in this release. If you explicitly choose it, consent and grant the named service permission, an authorisation attempt sends technical identifiers and a SHA-256 hash of the draft to Opace’s Google Cloud Run service in Belgium. The disabled channel rejects the attempt before draft upload. Use On this device or Quick checks only to avoid this request. The approximately 34.5 MB model and vocabulary download comes from opace.agency after consent. Its size and SHA-256 fingerprint are verified. The runtime ships inside the extension. Downloading model data does not upload your draft. Hosting infrastructure receives your IP address and request metadata when delivering model files or handling an optional EU authorisation attempt; ordinary hosting and security logs may contain this technical information. See the extension-specific section of our privacy policy. Cached model files can be removed with Clear everything stored. Requested content, page hostname and title are handled in memory. There is no background browsing monitor, telemetry or advertising. Drafts and page addresses are not saved in receipt history. Local storage holds settings and limited technical state. Clear everything stored removes this and cached model files; previously downloaded reports stay on your computer. Clicking the toolbar icon provides temporary access to the current page. No website access is granted at installation. Optional persistent access is requested for one named site and can be revoked in chrome://extensions. Browser pages, the Chrome Web Store and the built-in PDF viewer cannot be captured. The side-panel permission displays the workflow; scripting reads requested text; context menus provide selected-text capture; storage keeps settings; clipboard write supports explicit Copy actions. The extension never reads the clipboard. REPORTS AND SHARING PDF and HTML reports include the passages checked. JSON receipts and share summaries omit draft text and source URLs. Content Credentials reports omit filenames and file bytes. Review reports before sharing them. HONEST LIMITATIONS An AI reading is a pattern assessment, not proof of authorship or a percentage of words written by AI. Human writing can be flagged and AI writing can be missed. Short passages, fiction and heavily edited text need particular care. Do not use a result alone for academic misconduct or employment decisions. Character checks and editorial suggestions measure different things from the model. No hidden characters does not mean human-written. Quick checks only supplies no AI reading. Unavailable checks are identified explicitly. Model-based individual-sentence marking remains disabled; section evidence and separate quoted observations are available. This is not a plagiarism checker or fact-checking service. It cannot reliably identify a generator or verify or remove private Google or Anthropic production text watermarks. Missing Content Credentials are inconclusive; local signature checks do not establish certificate trust. FREE USE No subscription, Opace account or provider API key is needed. On-device checks have no run-count limit. Each check accepts up to 50,000 characters; longer input is refused rather than silently cut. NEW IN 1.2.3 Quoted writing observations, consistent section evidence in the panel and reports, compact controls, corrected page capture, responsive results and easier navigation back to the report. DOCUMENTATION AND SUPPORT Product: https://opace.agency/tools/ai/content-verification-integrity/chrome-extension/ Source, licence, credited dependencies and issues: https://github.com/OpaceDigitalAgency/opace-ai-content-checker-detector Research: https://opace.agency/tools/ai/content-verification-integrity/research/methodology/ Privacy: https://opace.agency/privacy-policy/ Support: https://opace.agency/get-in-touch/ Online checker: https://opace.agency/tools/ai/content-verification-integrity/checker/ WordPress version: https://opace.agency/tools/ai/content-verification-integrity/wordpress-plugin/ Astro integration: https://opace.agency/tools/ai/content-verification-integrity/astro-integration/ Opace open-source tools: https://github.com/OpaceDigitalAgency Custom AI development: https://opace.agency/services/artificial-intelligence/ Built by Opace, an independent UK digital agency. Opace is not affiliated with Google, Anthropic or other model providers.