Allure Fetch reference

Attachment schema

Each HTTP exchange is recorded as a JSON attachment with content type application/vnd.allure.http+json and file extension .httpexchange. The root object has the following shape:

Field	Type	Description
schemaVersion	1	Schema version. Always 1.
start	number	Unix timestamp in milliseconds when the request started.
stop	number	Unix timestamp in milliseconds when the response or error was received.
request	object	Captured request data. See Request.
response	object	Captured response data. Present only when a response was received. See Response.
error	object	Error information. Present only when the request failed. See Error.

Request

Field	Type	Description
method	string	HTTP method in uppercase, e.g. "GET".
url	string	Request URL, including query parameters in their original unredacted form.
headers	{name, value}[]	Request headers after redaction. Omitted when there are no headers.
query	{name, value}[]	Query parameters parsed from the URL, after redaction. Omitted when there are no query parameters.
cookies	Cookie[]	Cookies parsed from the Cookie request header, after redaction. Omitted when there are no cookies. See Cookie.
body	object	Request body. Present only when captureRequestBody is true and a body was sent. See Body.

Response

Field	Type	Description
status	number	HTTP status code.
statusText	string	HTTP status text.
headers	{name, value}[]	Response headers after redaction. Omitted when there are no headers.
cookies	Cookie[]	Cookies parsed from Set-Cookie response headers, after redaction. Omitted when there are no Set-Cookie headers. See Cookie.
body	object	Response body. Present only when captureResponseBody is true and a body was received. See Body.

Request and response bodies are captured from cloned Request and Response objects before they are consumed, so the Response returned to your test code remains fully readable.

Body

Field	Type	Description
contentType	string	Value of the Content-Type header. Absent when no Content-Type header is present.
encoding	"utf8" | "base64"	Encoding used for value. Present for all captured bodies except multipart. See Body encoding.
value	string	The captured body content, encoded per encoding. Present for all captured bodies except multipart.
size	number	Body size in bytes. See Body size.
truncated	boolean	true when the body exceeded maxBodySize and was cut off.
form	{name, value}[]	Structured fields parsed from a application/x-www-form-urlencoded body, after redaction. See URL-encoded form bodies.
stream	object	Present alongside value when the body was truncated during streaming. See Stream bodies.
parts	object[]	Structured parts for multipart/form-data bodies. See Multipart bodies. Present instead of value, encoding, and stream.

Body encoding

encoding is determined by the Content-Type header:

• Text content types — text/*, application/json, application/javascript, application/x-www-form-urlencoded, application/xml, or any type ending in +json or +xml → "utf8".
• No Content-Type header → "utf8" (treated as text).
• All other content types → "base64".

URL-encoded form bodies

When the content type is application/x-www-form-urlencoded, the body contains two representations of the same data:

• value: the re-serialized URL-encoded string, with sensitive fields replaced by the redaction placeholder.
• form: a structured {name, value}[] array with the same redaction applied.

Stream bodies

When a body exceeds maxBodySize, reading stops and the stream field appears alongside value to indicate partial capture:

Field	Type	Description
complete	boolean	Always false when stream is present.
type	string	Stream type derived from the content type: text/event-stream → "server-sent-events", application/grpc → "grpc", all others → "chunked".

When stream is present, value contains the captured bytes up to maxBodySize and truncated is true.

Multipart bodies

When the content type is multipart/form-data, the body is parsed via the Web API formData() method and stored as a parts array instead of value. Each part is one of:

• Text field: { name, encoding: "utf8", value, size, truncated: false }. Sensitive field values are redacted.
• File part: { name, fileName?, contentType?, size, truncated: false }. File contents are not captured; only the metadata is recorded.

Body size

The size field uses the Content-Length header when present. If Content-Length is absent and the body was fully captured within maxBodySize, size is the actual byte count. If Content-Length is absent and the body was truncated, size is omitted.

Cookie

Request cookies are parsed from the Cookie header. Response cookies are parsed from Set-Cookie headers.

Field	Type	Description
name	string	Cookie name.
value	string	Cookie value, after redaction.
path	string	Path attribute. Response cookies only.
domain	string	Domain attribute. Response cookies only.
expires	string	Expires attribute. Response cookies only.
httpOnly	boolean	true when the HttpOnly attribute is present. Response cookies only.
secure	boolean	true when the Secure attribute is present. Response cookies only.
sameSite	string	SameSite attribute value. Response cookies only.

Error

Present when the request failed. In fetch, this occurs for transport errors (e.g., network failure), aborts (via AbortController), and response body stream errors. HTTP error responses (4xx and 5xx) are not errors — they produce a normal response with no error field.

Field	Type	Description
name	string	The error's name property.
message	string	The error message.
stack	string	Stack trace. Present only when includeErrorStack is true.

Redaction types

RedactionMatcher

A RedactionMatcher controls whether a specific field value should be redacted. It can be any of the following:

• A string: redacts any field whose name equals the string, case-insensitively.
• A RegExp: redacts any field whose name matches the pattern.
• A function (name: string, value: string, context: RedactionContext) => boolean: redacts based on any logic, with access to the field name, value, and surrounding context.

withAllure(fetch, {
  redactHeaders: [
    "x-api-key", // exact name, case-insensitive
    /^x-internal-/i, // regex on the header name
    (name, value) => value.startsWith("sk-"), // match on the value itself
  ],
});

RedactionContext

The context argument passed to a function RedactionMatcher:

Property	Type	Description
kind	"header" | "query" | "cookie" | "form"	Which category is being evaluated.
name	string	The field name.
value	string	The field value.
url	string | undefined	The request URL.
request	Request | undefined	The Web API Request object.
response	Response | undefined	The Web API Response object. Present only when evaluating response-phase fields (response headers, response cookies).