text/html.html.htmtext/css.csstext/javascript.js.mjstext/plain.txttext/csv.csvtext/xml.xmltext/markdown.md.markdowntext/calendar.icstext/tab-separated-values.tsvtext/vcard.vcf.vcardimage/jpeg.jpg.jpegimage/png.pngimage/gif.gifimage/webp.webpimage/svg+xml.svg.svgzimage/avif.avifimage/bmp.bmpimage/tiff.tif.tiffimage/ico.icoimage/x-icon.icoimage/heic.heicimage/apng.apngaudio/mpeg.mp3audio/ogg.oga.oggaudio/wav.wavaudio/webm.webaaudio/flac.flacaudio/aac.aacaudio/midi.mid.midiaudio/opus.opusaudio/mp4.m4avideo/mp4.mp4.m4vvideo/webm.webmvideo/ogg.ogvvideo/mpeg.mpeg.mpgvideo/quicktime.mov.qtvideo/x-msvideo.avivideo/3gpp.3gpvideo/x-matroska.mkvvideo/x-ms-wmv.wmvapplication/json.jsonapplication/ld+json.jsonldapplication/xml.xmlapplication/pdf.pdfapplication/zip.zipapplication/gzip.gzapplication/x-tar.tarapplication/x-7z-compressed.7zapplication/x-rar-compressed.rarapplication/javascript.jsapplication/ecmascript.esapplication/typescript.tsapplication/wasm.wasmapplication/octet-stream.*application/x-www-form-urlencoded-multipart/form-data-application/graphql.graphqlapplication/sql.sqlapplication/x-sh.shapplication/x-python-code.pycapplication/msword.docapplication/vnd.openxmlformats-officedocument.wordprocessingml.document.docxapplication/vnd.ms-excel.xlsapplication/vnd.openxmlformats-officedocument.spreadsheetml.sheet.xlsxapplication/vnd.ms-powerpoint.pptapplication/vnd.openxmlformats-officedocument.presentationml.presentation.pptxapplication/vnd.oasis.opendocument.text.odtapplication/vnd.oasis.opendocument.spreadsheet.odsapplication/vnd.oasis.opendocument.presentation.odpfont/ttf.ttffont/otf.otffont/woff.wofffont/woff2.woff2font/collection.ttcmultipart/mixed-multipart/alternative-multipart/related-message/rfc822.eml.mhtmessage/partial-application/json.jsonREST API responses, config files
text/html.htmlWeb pages served by browsers
text/css.cssStylesheets for web pages
text/javascript.jsJavaScript files (IANA official)
multipart/form-dataFile uploads in HTML forms
application/pdf.pdfDocument downloads & previews
image/webp.webpModern web images (best compression)
application/octet-stream.*Generic binary / force download
application/wasm.wasmWebAssembly modules
MIME types appear in the Content-Type header of HTTP responses and requests:
HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
Content-Length: 1024
{"status": "ok"}
# File upload request:
Content-Type: multipart/form-data; boundary=----FormBoundary123
# Force browser download:
Content-Type: application/octet-stream
Content-Disposition: attachment; filename="report.xlsx"Content-Type: application/jsonCompare the extension and MIME value on the matching reference entry before setting a response header. The example below identifies a JSON response; the header describes the body format, not its filename. Use a format specific type when you know the content, and check the receiving application if it expects a particular subtype.
This reference does not inspect uploaded file bytes or configure your web server. A renamed file can retain content that differs from its extension. For downloads, Content-Disposition controls attachment handling alongside Content-Type; application/octet-stream alone is not an absolute instruction that every client must download. Verify the response headers after editing your server configuration, including any headers added by a proxy.
Content-Type: application/json
MIME (Multipurpose Internet Mail Extensions) type is a standard identifier used to indicate the nature and format of a document, file, or assortment of bytes. It consists of a type and subtype, e.g. 'text/html' or 'application/json'. Servers and browsers use MIME types to determine how to process files.
Set the Content-Type HTTP header to the appropriate MIME type. For example: Content-Type: application/json; charset=utf-8. Web servers like Apache and Nginx can map file extensions to MIME types automatically. In Express.js, use res.type('json') or res.setHeader('Content-Type', 'application/json').
application/json is the official IANA-registered MIME type for JSON data and should always be used. text/json is non-standard and was used historically. Modern APIs, frameworks, and browsers all expect application/json for JSON payloads.
Use application/octet-stream as a generic binary download type, which forces browsers to download rather than display the file. For specific formats use the appropriate type (e.g. application/pdf for PDFs). Combine with Content-Disposition: attachment; filename='file.ext' for a download prompt.