# Yangopen > Yangopen is a small personal studio building useful, carefully made products: a set of focused iPhone apps and a suite of free media tools. Most of the tools run entirely in the browser and never send your files anywhere; five of them — background removal, AI colorize, sharpen image, expand image and text to speech — use a server, and the privacy policy says so for each. Those five and the e-invoice converter have a free daily allowance; past it, the image tools, the premium voices and the invoice converter are paid for with prepaid credit. The site is bilingual. English lives at the root (e.g. `https://yangopen.com/apps/`) and Vietnamese under the `/vi/` prefix (e.g. `https://yangopen.com/vi/apps/`). Each page declares `hreflang` alternates linking its EN and VI versions. The full URL list is in the sitemap. Guiding principles: small and trustworthy, clear on the first tap, evidence before claims, open by default. The long form of this file is [llms-full.txt](https://yangopen.com/llms-full.txt): for each tool and app, its summary, how-to steps and questions and answers, taken from its own page, in English and Vietnamese. ## Apps - [PhaseSnap](https://yangopen.com/apps/phasesnap/): Organizes field photos by project, preserves clearly labeled device context, and creates on-device PDF and ZIP reports. - [Dharma Mala](https://yangopen.com/apps/dharmamala/): A mala counter for Vajrayana practice on iPhone and Apple Watch, with backfill for missed days and the Phugpa Tibetan calendar; on the App Store. - [Lantern of Văn Lang](https://yangopen.com/apps/lantern-van-lang/): A one-finger action roguelite for iPhone set in Vietnamese myth, where night falls 37 seconds into every run; pay once, no ads, fully offline, collects no data; waiting for App Store review, coming soon to the App Store. - [Đèn Về Bến](https://yangopen.com/apps/den-ve-ben/): A color puzzle game for iPhone: tap a lantern and it flies along its light beam to the boat of the same color; 200 levels, free with optional in-app purchases, no ads, plays offline; in TestFlight testing, coming soon to the App Store, not available in Vietnam. - [Snip & Splash](https://yangopen.com/apps/snipsplash/): A rope-cutting logic puzzle game for iPhone, for kids and grown-ups: cut ropes to drop the monsters into the pond and keep the chicks safe; 100 levels in 5 worlds, the first 40 free, one purchase unlocks the rest, no ads, plays offline, collects no data; coming soon to the App Store, not available in Vietnam. - [ChillPenny](https://yangopen.com/apps/chillpenny/): An iPhone app that plans a hangout from the money you want to spend: places near you from Apple Maps, an estimated price per person, a schedule that fits your limit and bill splitting with VietQR codes; no account, no ads, plans stay on the iPhone; free with a one-time Pro purchase; in Vietnamese; coming soon to the App Store. - [PaperHear](https://yangopen.com/apps/paperhear/): Listen to PDFs, articles, scans and notes on iPhone, then return to the exact sentence where you stopped. - [Weatherglass](https://github.com/yangyang1508/weatherglass): A tiny open-source menu bar app for Mac (MIT license) that reads the real weather every 15 minutes and shows it on screen: rain runs down the glass, snow settles on top of windows; free download from GitHub. ## Tools (in your browser; free runs every day) Tools that run entirely on-device say "on-device" below. The ones that send data away say so too — including the ones that send it to someone other than us. What reaches our own servers is not kept after the result is returned, except files used through an AI assistant (kept 24 hours, see below). - [Convert](https://yangopen.com/tools/convert/): Universal on-device file converter — images, audio, video, documents and data. Fast, unlimited, nothing leaves the browser. - [Audio to Text](https://yangopen.com/tools/audio-to-text/): Convert speech, audio and video to text or subtitles. Live dictation uses your browser's own speech recognition (the audio goes to Google or Microsoft, whichever your browser uses); file transcription sends the file straight to Groq with your own API key, not through our servers. (Sends data away, not on-device.) - [Text to Speech](https://yangopen.com/tools/text-to-speech/): Turn text into natural AI speech in Vietnamese, English and more. Standard voices are free and synthesised by an outside speech service (the text passes through our servers to it, not stored); premium voices are synthesised on Yangopen's own servers. Either way the text is not stored. Download WAV (made in the browser), MP3 or M4A (converted on our server, not kept). (Server-based, not on-device.) Also inside Claude and other AI assistants through the MCP connector (see "Use from an AI assistant" below): free voices from the account's daily allowance, Plus voices at 25 credits per 1,000 characters, charged only when the MP3 is ready; MP3 link valid 24 hours. - [Image to Text (OCR)](https://yangopen.com/tools/image-to-text/): Extract text from images, screenshots, scanned documents and PDFs (up to 300 pages) in the browser. On-device OCR in WebAssembly; a PDF page that holds its own text is read from it directly. - [Remove Background](https://yangopen.com/tools/remove-background/): Remove an image background in one click for a transparent PNG. Processed on a server, in memory, never stored. (Server-based, not on-device.) - [Colorize](https://yangopen.com/tools/colorize/): Colorize black-and-white and sepia photos automatically. High Quality processes on a server (in memory, never stored); Fast Mode runs entirely on your device. - [Expand Image](https://yangopen.com/tools/expand-image/): Grow a photo beyond its edges and change its shape to 16:9, 1:1 or 9:16. The new area is painted by AI; the original pixels are untouched. Runs on our server and an outside cloud AI service, in memory, never stored. - [Scan Document](https://yangopen.com/tools/scan-document/): Turn a phone photo of a page into a flat, straight scan: an AI model finds the page, removes what is around it and straightens tilt and curves, keeping the page's proportions. Runs on our server (in memory, never stored) or, if the reader picks it, entirely on their device. The scan opens in Image to text in one click. - [Sharpen Image](https://yangopen.com/tools/sharpen-image/): Sharpen and enhance photos with a before/after slider; High Quality enlarges a photo of 1200 px or less to at most 1920 px, and a larger photo keeps its size. High Quality processes on a server (in memory, never stored); Fast runs entirely on your device. - [Compress Image](https://yangopen.com/tools/compress-image/): Compress JPEG, PNG or WebP in the browser. Keeps JPEG EXIF unless you untick it. No upload. - [Compress Video](https://yangopen.com/tools/compress-video/): Compress MP4 or WebM in the browser — lower resolution and bitrate. No upload. - [Cut Video](https://yangopen.com/tools/cut-video/): Cut an MP4, MOV, WebM or MKV video at the exact frame you choose — most of the clip is copied from the original, not encoded again, so it keeps its quality and a shorter clip is a smaller file. Runs in the browser. No upload. - [Edit Video](https://yangopen.com/tools/edit-video/): CapCut-style video editing in the browser — timeline, text, subtitles from speech (a small speech model served from this site), export. On-device, no upload; no text to speech. - [Compare Images](https://yangopen.com/tools/compare-images/): Compare before/after with a slider, then export the split view, as you see it, as one JPEG. Runs in the browser. No upload. - [E-invoice XML to Excel](https://yangopen.com/tools/invoice-xml-to-excel/): Turn many Vietnamese e-invoice XML files (or ZIP files of them) into one Excel file, read on-device in your browser; only the number of invoices is sent, to count the free invoices of each day, after which prepaid credit is used. - [Merge PDF](https://yangopen.com/tools/merge-pdf/): Combine several PDF files into one, in the order you drag them; turn whole files. Runs in the browser. No upload. - [Split PDF](https://yangopen.com/tools/split-pdf/): Take pages out of a PDF, or delete, turn and reorder them; save the chosen pages, every page alone, typed ranges (as a ZIP) or the whole edited file. Runs in the browser. No upload. - [Images to PDF](https://yangopen.com/tools/images-to-pdf/): Put JPG, PNG, WebP or phone photos into one PDF, one picture per page, on A4, Letter or picture-size pages; sideways phone photos are turned upright. Runs in the browser. No upload. - [PDF to Images](https://yangopen.com/tools/pdf-to-images/): Save the pages of a PDF, or the pages you choose, as JPG or PNG pictures at 72, 150 or 300 dpi. Runs in the browser. No upload. - [Edit PDF](https://yangopen.com/tools/edit-pdf/): Click a line of a PDF to change its text, add text, white out, highlight or place a picture, then download the file. Changed lines are real text in an embedded font; a page with a white-out is saved as a picture so the covered words are gone. Runs in the browser. No upload. - [Sign PDF](https://yangopen.com/tools/sign-pdf/): Draw, type or upload a signature and place it on any page with a date or a line of text, then download the signed PDF. A picture of a signature, not a digital (certificate) signature. Runs in the browser. No upload. - [Translate PDF](https://yangopen.com/tools/translate-pdf/): Translate the text of a PDF between Vietnamese, English, Chinese, Japanese, Korean, French, German, Spanish, Portuguese, Italian, Russian, Thai and Indonesian, written back over each page so the layout, tables and pictures stay. Chrome and Edge on a computer translate on the device; other browsers send the text of the pages (never the file) to Yangopen's server and an outside cloud AI service, not stored. Server translation has free pages every day, then prepaid credit per page. The translated words are drawn as pictures; a .txt download carries the text. - [PDF to Word](https://yangopen.com/tools/pdf-to-word/): Turn a PDF into an editable Word (.docx) file on-device: text, headings and tables come from the PDF's own text; scanned pages and words held in pictures are read with OCR in the language picked (Vietnamese, Tibetan, Chinese, Japanese, Korean, Thai, Khmer, Lao, Burmese, Hindi, Sanskrit, Russian, French, German, Spanish, each with English; the OCR engine loads from jsDelivr). Two styles: Easy to edit, or Keep layout (each line a text box where it stood). No upload. - [Word to PDF](https://yangopen.com/tools/word-to-pdf/): Turn a Word file (.docx or .doc) into a PDF. On your device, free with no upload: real text in an embedded font (Tinos), Vietnamese letters right, headings, lists and tables kept. On our server (free files every day, then credit): the Word layout with pictures, headers and page numbers, old .doc files too; the file is deleted as soon as the PDF is returned. - [HEIC to JPG](https://yangopen.com/tools/heic-to-jpg/): Convert iPhone HEIC/HEIF photos to JPG or PNG on-device, up to 200 at a time, downloaded one by one or as a ZIP. Safari reads HEIC itself; other browsers load a HEIC reader from yangopen.com. No upload. - [Compress PDF](https://yangopen.com/tools/compress-pdf/): Make a PDF smaller on-device: its pictures are saved again as JPEG at the resolution they are shown (200, 150 or 100 dpi), repeated pictures and fonts kept once, unused objects dropped; text, fonts and vector drawings are not touched, and the text of the result is checked against the original before it is offered. No upload. - [Resize & add logo](https://yangopen.com/tools/resize-image/): Resize up to 200 photos at once to one size (1080 × 1080, 1080 × 1350, 1080 × 1920, 1200 × 630, 1280 × 720, a longest side of 1600 px, or your own), cropped to fill or fitted on white, black or a blurred copy of the photo, and stamp the same logo or text on each, in one of nine places or repeated across the photo. JPG, PNG or WebP, one by one or as a ZIP. Runs on-device; the logo is kept in your browser for next time. No upload. - [ID photo](https://yangopen.com/tools/id-photo/): Make a Vietnamese ID photo from one portrait: 3 × 4, 4 × 6 (passport), 2 × 3 cm, 3.5 × 4.5 cm (visa) or 5 × 5 cm (US visa); the background removed and made white or blue, the face found and the head sized and placed by the size's rule, then a 300 dpi JPG and a 10 × 15 cm print sheet of copies. Both models run in the browser. No upload. - [VNI & TCVN3 to Unicode](https://yangopen.com/tools/font-to-unicode/): Turn text typed in the old Vietnamese fonts (.VnTime and the other TCVN3/ABC fonts, VNI-Times and the other VNI fonts) into Unicode: pasted text (its table guessed from the characters), Word .docx, Excel .xlsx, .txt and .csv. In a file, only text set in an old font is changed, read through its own font's table, and that font becomes Times New Roman or Arial; formulas are not changed. On-device, no upload. - [Time Zone Converter](https://yangopen.com/tools/time-zone-converter/): The time now in your own place and the places you add, or any time and date in one of them ("9:00 on 30 August 2026 in London": three fields, Time, Date and In, or a slider) shown in all the others, each with its weekday, date and difference from you. Daylight saving comes from the browser's own time zone data, so every date has its own offsets. Copies the times or a link to them. About 100 cities by Vietnamese or English name, abbreviations (PST, JST) and UTC offsets, plus every zone the browser knows. Runs in the browser. Nothing is sent. ## Use from an AI assistant (MCP) - [AI assistants](https://yangopen.com/account/ai/): Add https://yangopen.com/mcp as a remote MCP connector (Claude: Customize → Connectors; Claude Code: `claude mcp add --transport http --scope user yangopen https://yangopen.com/mcp`), then connect a Yangopen account once (OAuth). Tools: text to speech (free and Plus voices), remove background, colorize, sharpen, expand image, scan document, Word to PDF (a photo or Word file goes in through a one-hour upload link; results are links valid 24 hours; 5 free runs a day per tool, then 25 credits a run, charged only when the result is ready), and two free text tools: old Vietnamese fonts (TCVN3, VNI) to Unicode, and a time between time zones. ## Guides (step by step, English and Vietnamese) - [All guides](https://yangopen.com/guides/): Each guide solves one task with a free Yangopen tool; Vietnamese at /vi/guides/. - [Put product photos on a white background for Shopee and TikTok Shop](https://yangopen.com/guides/white-background-product-photos/): Remove product photo backgrounds with AI: a 1024×1024 white square with the product centred, plus a transparent PNG. Up to 10 photos at once, free daily. - [Add a logo to photos in bulk and resize them for Shopee and TikTok Shop](https://yangopen.com/guides/resize-photos-add-logo/): Resize up to 200 photos to 1080×1080 or 1080×1920 and put the same logo or shop name on each, in your browser. Free; the photos never leave your device. - [Fix a blurry photo: save product shots before you list them](https://yangopen.com/guides/fix-blurry-product-photos/): Sharpen blurry or small product photos with AI; photos of 1200 px or less grow up to 1920 px. Know which blur can be fixed and which photo needs a reshoot. - [Compress images without visible quality loss: smaller product photos](https://yangopen.com/guides/compress-product-photos/): Make product photos smaller in your browser: set quality and longest side, compare with the original, then download. Nothing is uploaded; free, no limit. - [Expand an image with AI: turn a horizontal photo into 9:16 or 1:1 without cropping](https://yangopen.com/guides/expand-photo-vertical-square/): Turn a horizontal photo into a 9:16 or 1:1 one without cropping: AI paints new background around the edges, the original is kept. Free daily, not stored. - [Convert HEIC to JPG in bulk: iPhone photos ready to list and share](https://yangopen.com/guides/iphone-heic-to-jpg/): Convert up to 200 iPhone HEIC photos to JPG or PNG in your browser, about a second each, and download one ZIP. Free, no account, and no photo is uploaded. - [Claude MCP connector: use Yangopen's photo and voice tools inside Claude](https://yangopen.com/guides/claude-mcp-connector/): MCP lets Claude use another service's tools. Add yangopen.com/mcp to remove backgrounds, sharpen and expand photos, and read text aloud as MP3 in chat. ## About - [About Yangopen](https://yangopen.com/about/): What the studio is and how it works. - [Contact](https://yangopen.com/contact/): Reach out directly; every thoughtful message is read and answered. - [Apps overview](https://yangopen.com/apps/): Index of all products and tools. - [Pricing](https://yangopen.com/pricing/): Free allowances per tool, and one-time credit packs for AI work on our servers. No subscription; credit does not expire. ## Optional - [Privacy](https://yangopen.com/privacy/): Site-wide privacy approach. - [Sitemap](https://yangopen.com/sitemap.xml): Complete list of indexable EN/VI pages. - Per-app policies live under each app, e.g. `https://yangopen.com/apps/phasesnap/privacy/`, `/support/` and `/terms/`.