Privacy policy

This Privacy Policy applies to Stackflyer's website, editor, post downloader, LinkLift, Substack search tool, and related support communications. Stackflyer is an independent writing tool and is not affiliated with Substack Inc.

• Draft and project data. This includes titles, drafts, idea briefs, audience notes, voice samples and profiles, saved versions, and AI outputs you choose to keep.
• Anonymous workspace data. Stackflyer creates a random workspace key in your browser. The key itself is stored on your device; our database uses a one-way hash to associate your saved projects with that workspace.
• AI requests. When you run an AI tool, the text you submit, your selected instruction, and relevant writing context are sent for processing. Drafts are not sent to the AI provider merely because you type or save them.
• Downloader requests. When you use the post downloader, Stackflyer receives the URL you submit and temporarily fetches the publicly accessible page to create your requested files. The fetched article and converted files are not saved to your workspace or cached by the downloader.
• LinkLift data. When you create a LinkLift, we store the source and destination URLs, social-card title and description, cover-image URL, optional campaign tag, sharing text, creation time, and an approximate count and time of human opens. We do not store the article body for this feature.
• Search requests. When you use Search on Substack, Stackflyer receives your query and selected filters and sends them to Substack's public search service to return results. Stackflyer does not save search history or research lists to its database.
• Technical data. Our hosting and security systems may process IP address, request time, device or browser details, error information, and similar network data needed to deliver and protect the service.
• Messages you send us. If you email us, we receive your email address and the information you include.

We use information to provide cloud saving and version history, generate the editing output you request, secure and rate-limit the service, troubleshoot errors, and respond to support or privacy requests. We may use product feedback and technical error information to improve Stackflyer. We do not sell personal information, use your drafts for targeted advertising, or use saved drafts to train a Stackflyer model.

Stackflyer currently uses DeepSeek to generate AI editing results. When you intentionally run an AI tool, the submitted manuscript and relevant context are transmitted to DeepSeek for processing. DeepSeek may process data in the People's Republic of China and other locations described in its Privacy Policy. Do not submit passwords, financial information, health data, government identifiers, confidential client material, or other sensitive information.

We also rely on infrastructure providers, including OpenAI Sites and Cloudflare services, to host the application, database, and network layer. These providers may process technical and stored data only as needed to deliver their services and meet security or legal obligations. Search queries are transmitted to Substack to retrieve the public results you request and are subject to Substack's own privacy practices. If a direct request is unavailable from our hosting network, Stackflyer may use Jina AI Reader as a retrieval proxy; in that case, the query and requested Substack URL are also processed by Jina AI to return the same public data.

Stackflyer uses browser storage to keep your anonymous workspace key, active draft preference, a local fallback copy of project data, the research list you save from search results, and the management keys for LinkLifts created in that browser. Those LinkLift keys let the device edit, review, or deactivate its links and are not sent elsewhere except when you manage a link. The research list remains on your device unless you copy or export it. We do not currently use advertising cookies or third-party ad trackers. Your browser or hosting provider may still use essential technologies required for security and delivery.

Projects, versions, and saved AI outputs remain in your anonymous workspace until you delete them or the beta service is retired. You can delete individual projects from the Draft Library and export drafts you want to keep. Technical logs and residual backup copies may be retained for a limited period for security, continuity, fraud prevention, or legal compliance.

Your workspace key is the only practical way to reconnect the current browser to its anonymous cloud workspace. Clearing browser storage or changing devices may make the workspace inaccessible. Export important work before clearing browser data.

We use reasonable technical and organizational safeguards, including server-side API credentials, workspace-key hashing, access checks, and transport encryption. No online service is completely secure, so you should keep independent copies of important work and avoid storing highly sensitive information in Stackflyer.

You can access, export, correct, and delete project content through the editor. Depending on where you live, you may also have rights to request access, deletion, correction, portability, restriction, or objection regarding personal information. Email hello@stackflyer.com with the subject “Privacy request.” We may need enough information to verify and locate the relevant data without asking you to disclose your workspace key.

Stackflyer is not directed to children under 13 or the minimum age required in their location. We do not knowingly collect personal information from children. Contact us if you believe a child has provided personal information through the service.

Stackflyer and its providers may process information outside the country where you live. Where required, we rely on available legal mechanisms and provider safeguards for those transfers. By choosing to run an AI tool, you direct Stackflyer to transmit the submitted content to the AI provider described above.

We may update this policy as the product, providers, or law changes. We will post the updated date on this page and provide additional notice when required. Questions or privacy requests can be sent to hello@stackflyer.com.