YangOpen

Colour a black-and-white or toned (sepia) photo, with faces restored. A photo that already has colour comes back as it was and costs nothing. 5 free runs a day for each image tool, then 25 credits a run, charged only when the result is ready. Give the photo as file_id (the user uploads it through get_upload_link) or image_url. The result link works for 24 hours; give it to the user exactly as returned.

What a time in one place is in other places, with daylight saving applied for that date. Name zones the IANA way (Asia/Ho_Chi_Minh, America/New_York, Europe/London, Australia/Sydney) or UTC. Free.

Turn Vietnamese text typed in the old fonts (TCVN3/ABC such as .VnTime, or VNI such as VNI-Times) into Unicode, so it reads right in any font: "Céng hßa x· héi chñ nghÜa" becomes "Cộng hòa xã hội chủ nghĩa". The old font is guessed from the text unless you name it. Up to 5,000 characters a call. Free. For a whole Word or Excel file, send the user to https://yangopen.com/vi/tools/font-to-unicode/.

Extend a photo with AI-painted surroundings: to a new shape such as 16:9 (a cover), 9:16 (a phone story) or 1:1, or by a share of its size on the sides you choose. It never crops: the original pixels stay as they were. Can take up to a minute. 5 free runs a day for each image tool, then 25 credits a run, charged only when the result is ready. Give the photo as file_id (the user uploads it through get_upload_link) or image_url. The result link works for 24 hours; give it to the user exactly as returned.

The user's YangOpen credit balance, what it buys (Plus voice characters, paid image runs), the prices, and where to top up. Changes nothing.

A one-time page where the user uploads a file for the tools that need one: a photo (JPEG, PNG or WebP) for the image tools and scan_document, or a Word file (.docx or .doc) for word_to_pdf, up to 25 MB. It gives the file_id to pass to them. You cannot hand over a file from this chat yourself: give the user the link, ask them to open it and choose the file, and continue when they say it is done. In a client that can run shell commands (Claude Code), upload a local file yourself with the upload_command. The link works for 1 hour; the file is kept for 24 hours. Free.

The YangOpen voices. tier "free" (default): sixteen free voices — two Vietnamese (Southern accent), American and British English, Mandarin, Japanese, Korean, Thai, French and Spanish. tier "plus": the paid voices, about 2,600 — 182 Vietnamese (Northern, Central and Southern), English, Spanish, Mandarin, French, Japanese and Korean; search them by language, gender and words in the name or style. Returns the id to pass to text_to_speech (free) or text_to_speech_plus (plus).

Cut the main subject out of a photo and get a PNG with a transparent background. 5 free runs a day for each image tool, then 25 credits a run, charged only when the result is ready. Give the photo as file_id (the user uploads it through get_upload_link) or image_url. The result link works for 24 hours; give it to the user exactly as returned.

Turn a phone photo of a page (a document, a receipt, a page of a book) into a flat, straight scan: the page is found, cut out of the background and unbent, and comes back as a JPEG. 5 free runs a day for each image tool, then 25 credits a run, charged only when the result is ready. Give the photo as file_id (the user uploads it through get_upload_link) or image_url. The result link works for 24 hours; give it to the user exactly as returned.

Make a blurry, small or old photo sharp and larger (AI upscaling). It can also restore faces, and clean scratches and dust from an old print. 5 free runs a day for each image tool, then 25 credits a run, charged only when the result is ready. Give the photo as file_id (the user uploads it through get_upload_link) or image_url. The result link works for 24 hours; give it to the user exactly as returned.

Turn text into speech with a free YangOpen voice and get a link to the MP3. It costs no credit; it counts against the user's free daily allowance. Up to 3,000 characters per call: split longer text at sentence ends and call once per part. The link works for 24 hours; give it to the user exactly as returned. The text is sent to an outside speech service to be read; it is not stored.

Turn text into speech with a Plus voice and get a link to the MP3. Spends the user's prepaid YangOpen credit: 25 credits per 1,000 characters, rounded up to whole credits. The charge is made only when the MP3 is ready, and the answer states what was charged and the balance left. Up to 1,000 characters per call for Vietnamese voices and 400 for the other languages; split longer text at sentence ends. Before a long job, tell the user the cost (characters ÷ 1,000 × 25 credits) and check get_balance. The link works for 24 hours; give it to the user exactly as returned.

Turn a Word document (.docx or .doc, up to 25 MB) into a PDF with the layout Word gave it, on YangOpen's server. A few hundred pages take under half a minute; a much longer document may not finish. 5 free files a day, then 25 credits a file, charged only when the PDF is ready. Give the file as file_id (the user uploads it through get_upload_link) or file_url. The PDF link works for 24 hours; give it to the user exactly as returned.