Paste a raw Content-Type value or full HTTP header block
EXAMPLES:
Ready to parse
Paste a MIME header and click Parse// inspect media type, charset, boundary, and mime parameters
Parse and inspect MIME headers instantly. Extract media type, charset, boundary, and all MIME parameters from Content-Type strings. Free browser-based tool.
Ready to parse
Paste a MIME header and click ParseEnter a raw Content-Type value like text/html; charset=utf-8 or a full HTTP header block.
The tool extracts media type, subtype, charset, boundary, and all custom parameters instantly.
Inspect each field, check for warnings, and copy the full parsed result as JSON.
The MIME Header Parser breaks down Content-Type and other MIME header strings into their individual components — media type, subtype, and all semicolon-separated parameters. It warns about missing required fields like boundary in multipart types and flags uncommon charsets.
MIME (Multipurpose Internet Mail Extensions) types are standardized identifiers that describe the nature and format of a document or file. They consist of a type and subtype separated by a slash, like text/html or application/json. Servers send them in Content-Type headers so browsers and clients know how to handle the data.
The charset parameter specifies the character encoding of text-based content. For example, text/html; charset=utf-8 tells the browser to decode the HTML using UTF-8 encoding. Missing or incorrect charsets can cause garbled text — especially with non-ASCII characters.
When a Content-Type is multipart/form-data or multipart/mixed, a boundary parameter is required. It defines a unique string that separates each body part in the request. Without a boundary, the server cannot parse the individual parts of the multipart message, making it a required field.
Yes. If you paste a full block of HTTP headers (including lines like Content-Length:, Accept:, etc.), the tool automatically finds and extracts the Content-Type line and parses it. You can also paste just the value directly — both formats work.
The parser handles all IANA-registered top-level types: application, audio, font, image, message, model, multipart, text, and video. It also accepts experimental and vendor-specific types (like application/vnd.api+json).
Parsing is handled server-side via a lightweight PHP API call on this domain. No data is stored, logged, or shared. The request is stateless and your header content is immediately discarded after the response is generated.
A MIME Header Parser is a tool that deconstructs Content-Type HTTP headers — and MIME headers in general — into their logical components. Every Content-Type value follows a predictable structure defined by RFC 2045 and RFC 7231: a top-level media type, a subtype, and an optional list of semicolon-separated parameters like charset, boundary, or name. While this format is straightforward in theory, debugging it in practice — especially across APIs, multipart uploads, and legacy systems — can be surprisingly tedious.
This tool exists to make that inspection instant. Paste any header string, and the parser breaks it into every meaningful field, flags structural issues, and presents the result in a clear, copyable format.
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The Content-Type header is one of the most important HTTP headers in existence. It appears in both requests and responses and tells the recipient exactly what kind of data is being transferred and how to interpret it. Without it (or with an incorrect value), browsers may render HTML as plain text, APIs may refuse to parse JSON, and file uploads may fail silently.
A typical Content-Type value looks like this:
text/html; charset=utf-8Breaking this down: text is the top-level type (meaning human-readable content), html is the subtype (specifying the HTML format), and charset=utf-8 is a parameter telling the client to decode the body as UTF-8 text. More complex examples appear in multipart form submissions:
multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gWHere, multipart/form-data signals that the body contains multiple independent sections (form fields and file data), and the boundary string is the delimiter that separates them. Both charset and boundary are so commonly misunderstood that entire classes of bugs exist around them.
MIME types are maintained by IANA (the Internet Assigned Numbers Authority), which defines the official top-level types and hundreds of registered subtypes. The main top-level types are:
Beyond these, vendor-specific types use the vnd. prefix (like application/vnd.api+json), and experimental types use x- (though this convention is now deprecated in favor of formal registration).
After the media type, parameters appear as key=value pairs separated by semicolons. These are the most important ones to know:
text/* type, RFC 2045 defaults to US-ASCII, which can cause problems with non-ASCII content.multipart/* types. It must be a unique string that does not appear in any of the body parts. Browsers generate this automatically for form submissions; servers must respect exactly the boundary specified in the header.Content-Disposition contexts to provide a filename hint for binary downloads.text/plain (e.g., format=flowed) to describe email body formatting.MIME header issues are more prevalent than most developers expect. They usually fall into a few recurring patterns:
text/plain when the client expects application/json causes JSON parsers to reject the response body, even if the content itself is valid JSON.text/html without a charset declaration forces browsers into content-sniffing mode, which can result in XSS vulnerabilities or garbled text.boundary in the header doesn't match the actual delimiter in the body, the server will fail to parse the request. No error message makes this obvious.Text/HTML equals text/html), but parameter values like the boundary string are case-sensitive. Normalizing incorrectly causes subtle failures.When working with REST APIs, the Content-Type header drives two critical behaviors: how the client encodes the request body and how the server interprets it. Mismatches between the two are a frequent source of 400 Bad Request errors. By pasting the exact header your API client is sending into this parser, you can instantly verify the media type, confirm the charset, and rule out formatting errors before diving into the request body itself.
This is particularly useful when working with proxies or middleware that may transform headers in transit. Many API gateways rewrite or append Content-Type parameters — checking the header that actually reaches the server (rather than what you think you're sending) is a habit that saves significant debugging time.
MIME was originally designed for email (Multipurpose Internet Mail Extensions), but its use in HTTP is nearly universal today. In email, MIME enables attachments, HTML formatting, and mixed content through multipart/alternative and multipart/mixed types. In HTTP, the same syntax describes request and response bodies. The parsing rules are identical — which means this tool works equally well for debugging email headers as it does for HTTP API headers.