Last updated: November 9, 2026
1. About Captionsly and this policy
Captionsly is a video-captioning app for iPhone and iPad running iOS or iPadOS 26 and later. It lets you import a portrait video, select a speech interval of up to 60 seconds, generate captions in a supported language on your device, edit their text, timing and appearance, save projects, and export a full-length MP4 with captions. The developer responsible for Captionsly is Christos Mountzouris (“we”, “us” or “our”). For privacy questions or requests, email support@mountzou.dev.
2. Videos you choose and on-device processing
You choose a video through Apple’s system Photos or Files picker. Captionsly receives the file you select; it does not request broad access to browse or scan your photo library. The video may contain personal information, including faces, voices, spoken words and embedded metadata. The app processes it locally to display previews, extract audio, show a waveform, create timed captions and render your export.
Speech recognition uses Apple’s SpeechAnalyzer with SpeechTranscriber, or DictationTranscriber for supported Greek recognition, on your device. Available languages depend on your device and Apple’s supported models. If a required language model is missing, the system may download it from Apple. The selected audio is not sent to Apple’s speech-recognition servers for this transcription. Captionsly does not upload your videos, audio or captions to us, Firebase or a remote AI service, and we do not use them to train AI models. There is no Captionsly media-storage server. Account authentication, files you choose to share and information you voluntarily email to support are handled separately, as described below.
3. Local storage and retention
Captionsly automatically saves projects in its local app storage so you can resume editing. A project includes an independent copy of the imported video, a thumbnail, generated and corrected captions, word timings and appearance, project names, dates and identifiers, pin status, the selected language and speech interval, and editing state such as unfinished text, playback position, timeline zoom and undo history. The app also stores preferences such as appearance, caption length, recent languages and whether an editing hint has been shown. These project records and preferences are not sent to us. Captionsly does not provide account-based cloud backup or cross-device project synchronization.
Projects belong to the app installation on that device and are not separated by signed-in account. Signing out leaves the local library in place; signing in with another account on the same installation can make those projects available to that user. Signing in on another device does not transfer your projects.
Projects remain on the device until permanently deleted, removed through account deletion on that device, or removed with the app’s local data. Working files are also created for importing, audio extraction and export. Import staging copies and extracted audio are normally removed after their processing step finishes. Exported MP4s are created in temporary app storage; remaining temporary files may persist until the system reclaims them, account-deletion cleanup removes them, or the app is deleted. Save an export outside the app if you want to keep it.
Move to Trash keeps the project’s saved source copy, thumbnail, captions and editing records in local Trash so you can restore it for 30 days. After that period, expired projects are permanently removed when the app next checks Trash. You can permanently delete an item or empty Trash sooner. Removing projects does not delete originals in Photos or Files, exports saved elsewhere, or copies in backups.
Using Delete App removes the app’s local data; Offload App may preserve it. Removing the app does not delete your online Captionsly account. Local data may be included in device backups and may return when a backup is restored. Manage backups separately through your device or backup provider’s settings.
4. Exporting, sharing and permissions
Export creates a new full-length MP4 containing the video, its audio where present, and your visible captions. It does not overwrite your source video. Save to Photos adds a copy to your photo library. Share opens the system share sheet and passes the file to the destination you select, such as Files or another app. Photos, iCloud or another destination may upload or synchronize that copy under its own settings and privacy policy. Captionsly does not automatically publish or send your export to us.
The app uses system pickers for selecting media and does not request broad access to read your photo library. When you choose Save to Photos, it requests add-only Photos permission to save the exported video. You can decline or change this permission in device Settings and use Share instead. Imported source copies can retain embedded recording or location metadata. Captionsly does not provide a metadata-removal feature; exporting captions does not make the people, voices or information in your video anonymous.
5. Accounts, tracking and other information
Captionsly requires Sign in with Apple or Sign in with Google. We use Google’s Firebase Authentication to create and manage your Captionsly account and restore your session. Account information can include your Firebase user ID, the chosen sign-in provider and its account identifier, and the name and email address supplied by that provider. Apple may supply a private relay email address if you choose Hide My Email. Authentication credentials and tokens are exchanged with Firebase and the selected provider to verify you and maintain your session; Captionsly does not receive your Apple or Google password. The app displays available account details in Settings.
Firebase processes authentication information, IP addresses and user-agent information to operate sign-in and prevent abuse. Google Sign-In may also process account and device identifiers, sign-in service-use information and technical data; an IP address may be used to estimate general location for fraud prevention. Google’s SDK privacy disclosures include service analytics. This authentication processing is separate from local video and caption processing. See the Firebase privacy information and Google Sign-In data disclosures linked below.
To delete your account, open Settings → Delete account and confirm. The app asks you to verify the same Apple or Google identity again, revokes provider access and deletes the Firebase account. After account deletion succeeds, it permanently removes the app’s entire local Projects library, including Trash, and owned temporary media on that device. This includes projects created under another sign-in on the same installation. Originals and exports saved outside the app remain. If verification or server deletion fails, local projects are preserved. If local cleanup is interrupted after the account is deleted, the app asks you to finish cleanup when it next opens. This does not delete your Apple or Google account or erase projects stored on another device.
Account information is retained in Firebase until the account is deleted. Firebase states that logged IP addresses are retained for a few weeks and other authentication information is removed from its live and backup systems within 180 days after deletion is initiated. Apple and Google may retain separate security or service records under their own policies. Signing out or uninstalling Captionsly does not request account deletion. Contact us if you cannot access the in-app deletion flow.
Captionsly does not include advertising, tracking, Firebase Analytics or a third-party crash-reporting SDK, and does not send your editing activity or preferences to us. It does not request access to your device location, contacts, microphone or camera; it works with videos you select. The provider processing described above still applies when you use sign-in.
6. Service providers and external pages
A video stored in iCloud Photos, iCloud Drive or another Files provider may need to download before import. Speech language assets may also require a download from Apple. Device backups and destinations you choose for exports may synchronize data according to your settings. Apple may process App Store, device or diagnostic information and make certain analytics or crash reports available to developers, depending on its services and your sharing settings. We use any reports made available to us to understand reliability and improve Captionsly, not for advertising. These services are separate from Captionsly’s local caption processing.
A copy of this policy is hosted in Google Docs. Opening that copy may allow Google and your browser to process information such as your IP address and browser details under their own policies. Captionsly does not attach your videos, captions or project data to this page. See Apple’s Privacy Policy and Google’s Privacy Policy for their services, including international processing and applicable safeguards. For the authentication services described above, also see Firebase privacy information and Google Sign-In data disclosures.
7. When you contact support
If you email support@mountzou.dev, we receive your email address, message and any information or attachments you choose to include. We use that information to respond, troubleshoot and follow up on your request. Sending a video, audio file, transcript or screenshot is optional. Include only information needed for the issue, and avoid sending sensitive information or other people’s private content unnecessarily.
Support correspondence is handled through our email service provider. We retain support messages and any diagnostic reports we receive only as long as reasonably needed to address the inquiry, investigate the relevant reliability issue and handle related follow-up, or to meet an applicable legal obligation. We do not use support messages for unsolicited marketing, sell personal information, or share it for targeted advertising.
8. Your privacy rights and security
Under applicable data-protection law, you may request access, correction or deletion of personal information we hold about you and, where applicable, restriction, objection or data portability. You may also complain to your local data-protection authority. Contact support@mountzou.dev to exercise your rights. We respond within the time limits required by applicable law. Information held only on your device is managed through Captionsly, Photos, Files and your device settings; we cannot remotely access or erase your local projects or retrieve a deleted draft for you.
Where the GDPR applies, we process account information to provide and manage the sign-in service you request (performance of our contract with you). We rely on legitimate interests in protecting account security, preventing abuse, responding to voluntary support requests and investigating app reliability, where those interests are not overridden by your rights. Information that must be retained to meet a legal obligation is processed on that basis. Where processing relies on consent, you may withdraw it without affecting the lawfulness of earlier processing.
Google processes Firebase account data on our behalf under its applicable data-processing terms. Our email provider and the Apple and Google services described above may process information outside your country, including outside the European Economic Area. Applicable safeguards may include the EU–U.S. Data Privacy Framework and contractual protections, as described in the providers’ privacy and data-processing terms.
Captionsly relies on iOS app-storage and permission protections. No device or storage method can be guaranteed completely secure. Protecting access to your device, media library, email account and backups helps protect your information. Captions are generated automatically and may be inaccurate; you can review and correct them before exporting. Captionsly does not use transcription to identify speakers, create voiceprints or make decisions about people with legal or similarly significant effects.
9. Children
Captionsly is a general-purpose video-captioning app and does not ask for a date of birth. Sign-in uses Apple or Google accounts and is subject to the chosen provider’s account requirements. If you believe a child’s personal information has been provided to us through an account or support correspondence, contact us so that we can review and address it.
10. Changes and contact
We may update this policy if Captionsly’s features or privacy practices change. Updates will be posted on this page with a revised date. We will provide relevant notices and request consent where required before introducing processing that needs it.
Privacy contact: Christos Mountzouris · support@mountzou.dev.