Advanced capture mode

Under Options → Network you can choose the capture mode for network traffic:

Mode	In the UI	What it means
Classic mode	classic snapshot	Same limits as in-page interception: headers and bodies are only what page scripts can read (including CORS rules for cross-origin). See Working with requests.
Advanced mode	extended capture	The extension requests webRequest access and enriches the request details with the full set of request and response headers as seen by the browser for the exchange—not only the subset exposed to the page.

Advanced mode (pinning headers, Header links, Advanced-only header visibility options) is available only in the Chrome / Edge extension.
Standalone still runs without extended capture: the full header set via webRequest described below is not available there.

---

What Advanced mode adds in the Network tab

• Request and response headers in request details use the extended data (including headers not listed in Access-Control-Expose-Headers).
• Pinning header rows — a header name can be pinned to the top of the list separately for Request and Response. Pins are toggled from the row menu (three dots) when Advanced mode is on.
• Header links — for a given header name and request Host, open an external URL using a template; the {value} placeholder (and optional value pipeline) controls how the header text is inserted into the link. See Header links below.

The Header links list, Pinned headers table, and Advanced headers options under Options → Network are shown only when Advanced mode is enabled, so Classic mode stays uncluttered.

---

Header links

Each rule defines:

• Header — HTTP header name (matched case-insensitively);
• Host — host of the request URL (normalized: no scheme or path, e.g. api.example.com);
• Link — URL template; placeholders are resolved as described in Value placeholder and pipeline.

You can create and edit rules from the header row menu on the Network tab (Advanced) and from Options when a header rule group is selected.

Value placeholder and pipeline

Inside the Link field you can use:

• {value} — insert the header value exactly as shown on the request card (same as a pipeline with no steps).
• {value|…} — run a pipeline: after {value, list steps separated by |; apply them left → right, then insert the result. Example: {value|trim|urlencode}.

Use a pipe | between steps. The parser splits the chain at | only when the next segment starts with a known operation (see tables below). That way, a | inside a regex (e.g. alternation a|b) is usually fine, as long as the substring after a candidate split does not look like a new op.

If a step is invalid (e.g. bad regex), that step is skipped and the value is left unchanged for that step.

No-argument operations

Op	Effect
trim	Trim leading/trailing whitespace.
lower	Lowercase.
upper	Uppercase.
urlencode	encodeURIComponent-style encoding for use in URL query parts.
urldecode	Decode URI component (+ treated as space). Invalid escapes leave the value unchanged.
base64encode / base64decode	Base64 of UTF-8 bytes.
hexencode / hexdecode	Hex string ↔ UTF-8 bytes (hexdecode ignores whitespace).
md5	MD5 hex digest of UTF-8 input (sync).
sha1 / sha256	SHA-1 / SHA-256 hex digest via Web Crypto (crypto.subtle). Requires a context where SubtleCrypto is available (e.g. HTTPS or extension pages); otherwise the digest step yields an empty string.

Regex and replacement

Op	Syntax	Notes
regex	regex:<pattern>	new RegExp(<pattern>) (no flags in the syntax—add them inside the pattern if your engine supports it). Sets the last match for a following replace. On no match, the value becomes empty.
replace	replace:<template>	After replace:, substitute $1, $2, … from the last regex match. If there was no match, result is empty.
replaceRegex	replaceRegex:<pattern>:<template>	Pattern and template are split at the last : in the segment—so a : inside the pattern is awkward; prefer regex + replace instead. Uses String.replace with a RegExp.
match	match:<pattern>	If the value matches, keep it; otherwise replace with empty string.

Strings and structure

Op	Syntax	Notes
replaceText	replaceText:<from>:<to>	From / to use the last : in the payload as separator between to and everything before it (from may contain :). Global replace of all from occurrences. Empty from skips the step.
substring	substring:<start> or substring:<start>:<length>	Same idea as String.slice / substring: with two numbers, length is a character count from start.
split	split:<delimiter>:<index>	Index is the part after the last : (must be digits). Delimiter is everything before that : (may contain :). Empty part if index is out of range.

Conditions and defaults

Op	Syntax	Notes
default	default:<fallback>	If the current value is exactly the empty string after previous steps, set it to <fallback>. To treat whitespace-only as empty, use trim first.
ifMatch	ifMatch:<pattern>:<ifTrue>:<ifFalse>	False branch is after the last :; true branch is between the second-to-last and last :; pattern is everything before the second-to-last : (so colons inside branches are constrained by this rule).

Examples

https://trace.example.com/?id={value}

https://trace.example.com/?id={value|trim|urlencode}

https://trace.example.com/?t={value|regex:^Bearer\s+(.+)$|replace:$1|urlencode}

https://trace.example.com/?t={value|default:unknown}

Multiple placeholders in one template are allowed; each {value...} block is resolved independently using the same header value.

---

Quick recap

• Advanced mode extends headers via webRequest; Standalone does not provide this mode.
• Classic mode is the original “page-visible” header model.
• Pin — separate for Request / Response lists.
• Header links: Host + Link template: {value} or pipeline {value|op|…} for the header value.