diff --git a/Documentation/git-credential.txt b/Documentation/git-credential.txt
index b211440373..6f0c7ca80f 100644
--- a/Documentation/git-credential.txt
+++ b/Documentation/git-credential.txt
@@ -19,8 +19,7 @@ from system-specific helpers, as well as prompting the user for
 usernames and passwords. The git-credential command exposes this
 interface to scripts which may want to retrieve, store, or prompt for
 credentials in the same manner as Git. The design of this scriptable
-interface models the internal C API; see
-link:technical/api-credentials.html[the Git credential API] for more
+interface models the internal C API; see credential.h for more
 background on the concepts.
 
 git-credential takes an "action" option on the command-line (one of
diff --git a/Documentation/gitcredentials.txt b/Documentation/gitcredentials.txt
index adc759612d..ea759fdee5 100644
--- a/Documentation/gitcredentials.txt
+++ b/Documentation/gitcredentials.txt
@@ -186,8 +186,7 @@ CUSTOM HELPERS
 --------------
 
 You can write your own custom helpers to interface with any system in
-which you keep credentials. See the documentation for Git's
-link:technical/api-credentials.html[credentials API] for details.
+which you keep credentials. See credential.h for details.
 
 GIT
 ---
diff --git a/Documentation/technical/api-credentials.txt b/Documentation/technical/api-credentials.txt
deleted file mode 100644
index 75368f26ca..0000000000
--- a/Documentation/technical/api-credentials.txt
+++ /dev/null
@@ -1,271 +0,0 @@
-credentials API
-===============
-
-The credentials API provides an abstracted way of gathering username and
-password credentials from the user (even though credentials in the wider
-world can take many forms, in this document the word "credential" always
-refers to a username and password pair).
-
-This document describes two interfaces: the C API that the credential
-subsystem provides to the rest of Git, and the protocol that Git uses to
-communicate with system-specific "credential helpers". If you are
-writing Git code that wants to look up or prompt for credentials, see
-the section "C API" below. If you want to write your own helper, see
-the section on "Credential Helpers" below.
-
-Typical setup
--------------
-
-------------
-+-----------------------+
-| Git code (C)          |--- to server requiring --->
-|                       |        authentication
-|.......................|
-| C credential API      |--- prompt ---> User
-+-----------------------+
-	^      |
-	| pipe |
-	|      v
-+-----------------------+
-| Git credential helper |
-+-----------------------+
-------------
-
-The Git code (typically a remote-helper) will call the C API to obtain
-credential data like a login/password pair (credential_fill). The
-API will itself call a remote helper (e.g. "git credential-cache" or
-"git credential-store") that may retrieve credential data from a
-store. If the credential helper cannot find the information, the C API
-will prompt the user. Then, the caller of the API takes care of
-contacting the server, and does the actual authentication.
-
-C API
------
-
-The credential C API is meant to be called by Git code which needs to
-acquire or store a credential. It is centered around an object
-representing a single credential and provides three basic operations:
-fill (acquire credentials by calling helpers and/or prompting the user),
-approve (mark a credential as successfully used so that it can be stored
-for later use), and reject (mark a credential as unsuccessful so that it
-can be erased from any persistent storage).
-
-Data Structures
-~~~~~~~~~~~~~~~
-
-`struct credential`::
-
-	This struct represents a single username/password combination
-	along with any associated context. All string fields should be
-	heap-allocated (or NULL if they are not known or not applicable).
-	The meaning of the individual context fields is the same as
-	their counterparts in the helper protocol; see the section below
-	for a description of each field.
-+
-The `helpers` member of the struct is a `string_list` of helpers.  Each
-string specifies an external helper which will be run, in order, to
-either acquire or store credentials. See the section on credential
-helpers below. This list is filled-in by the API functions
-according to the corresponding configuration variables before
-consulting helpers, so there usually is no need for a caller to
-modify the helpers field at all.
-+
-This struct should always be initialized with `CREDENTIAL_INIT` or
-`credential_init`.
-
-
-Functions
-~~~~~~~~~
-
-`credential_init`::
-
-	Initialize a credential structure, setting all fields to empty.
-
-`credential_clear`::
-
-	Free any resources associated with the credential structure,
-	returning it to a pristine initialized state.
-
-`credential_fill`::
-
-	Instruct the credential subsystem to fill the username and
-	password fields of the passed credential struct by first
-	consulting helpers, then asking the user. After this function
-	returns, the username and password fields of the credential are
-	guaranteed to be non-NULL. If an error occurs, the function will
-	die().
-
-`credential_reject`::
-
-	Inform the credential subsystem that the provided credentials
-	have been rejected. This will cause the credential subsystem to
-	notify any helpers of the rejection (which allows them, for
-	example, to purge the invalid credentials from storage).  It
-	will also free() the username and password fields of the
-	credential and set them to NULL (readying the credential for
-	another call to `credential_fill`). Any errors from helpers are
-	ignored.
-
-`credential_approve`::
-
-	Inform the credential subsystem that the provided credentials
-	were successfully used for authentication.  This will cause the
-	credential subsystem to notify any helpers of the approval, so
-	that they may store the result to be used again.  Any errors
-	from helpers are ignored.
-
-`credential_from_url`::
-
-	Parse a URL into broken-down credential fields.
-
-Example
-~~~~~~~
-
-The example below shows how the functions of the credential API could be
-used to login to a fictitious "foo" service on a remote host:
-
------------------------------------------------------------------------
-int foo_login(struct foo_connection *f)
-{
-	int status;
-	/*
-	 * Create a credential with some context; we don't yet know the
-	 * username or password.
-	 */
-
-	struct credential c = CREDENTIAL_INIT;
-	c.protocol = xstrdup("foo");
-	c.host = xstrdup(f->hostname);
-
-	/*
-	 * Fill in the username and password fields by contacting
-	 * helpers and/or asking the user. The function will die if it
-	 * fails.
-	 */
-	credential_fill(&c);
-
-	/*
-	 * Otherwise, we have a username and password. Try to use it.
-	 */
-	status = send_foo_login(f, c.username, c.password);
-	switch (status) {
-	case FOO_OK:
-		/* It worked. Store the credential for later use. */
-		credential_accept(&c);
-		break;
-	case FOO_BAD_LOGIN:
-		/* Erase the credential from storage so we don't try it
-		 * again. */
-		credential_reject(&c);
-		break;
-	default:
-		/*
-		 * Some other error occurred. We don't know if the
-		 * credential is good or bad, so report nothing to the
-		 * credential subsystem.
-		 */
-	}
-
-	/* Free any associated resources. */
-	credential_clear(&c);
-
-	return status;
-}
------------------------------------------------------------------------
-
-
-Credential Helpers
-------------------
-
-Credential helpers are programs executed by Git to fetch or save
-credentials from and to long-term storage (where "long-term" is simply
-longer than a single Git process; e.g., credentials may be stored
-in-memory for a few minutes, or indefinitely on disk).
-
-Each helper is specified by a single string in the configuration
-variable `credential.helper` (and others, see linkgit:git-config[1]).
-The string is transformed by Git into a command to be executed using
-these rules:
-
-  1. If the helper string begins with "!", it is considered a shell
-     snippet, and everything after the "!" becomes the command.
-
-  2. Otherwise, if the helper string begins with an absolute path, the
-     verbatim helper string becomes the command.
-
-  3. Otherwise, the string "git credential-" is prepended to the helper
-     string, and the result becomes the command.
-
-The resulting command then has an "operation" argument appended to it
-(see below for details), and the result is executed by the shell.
-
-Here are some example specifications:
-
-----------------------------------------------------
-# run "git credential-foo"
-foo
-
-# same as above, but pass an argument to the helper
-foo --bar=baz
-
-# the arguments are parsed by the shell, so use shell
-# quoting if necessary
-foo --bar="whitespace arg"
-
-# you can also use an absolute path, which will not use the git wrapper
-/path/to/my/helper --with-arguments
-
-# or you can specify your own shell snippet
-!f() { echo "password=`cat $HOME/.secret`"; }; f
-----------------------------------------------------
-
-Generally speaking, rule (3) above is the simplest for users to specify.
-Authors of credential helpers should make an effort to assist their
-users by naming their program "git-credential-$NAME", and putting it in
-the $PATH or $GIT_EXEC_PATH during installation, which will allow a user
-to enable it with `git config credential.helper $NAME`.
-
-When a helper is executed, it will have one "operation" argument
-appended to its command line, which is one of:
-
-`get`::
-
-	Return a matching credential, if any exists.
-
-`store`::
-
-	Store the credential, if applicable to the helper.
-
-`erase`::
-
-	Remove a matching credential, if any, from the helper's storage.
-
-The details of the credential will be provided on the helper's stdin
-stream. The exact format is the same as the input/output format of the
-`git credential` plumbing command (see the section `INPUT/OUTPUT
-FORMAT` in linkgit:git-credential[1] for a detailed specification).
-
-For a `get` operation, the helper should produce a list of attributes
-on stdout in the same format. A helper is free to produce a subset, or
-even no values at all if it has nothing useful to provide. Any provided
-attributes will overwrite those already known about by Git.  If a helper
-outputs a `quit` attribute with a value of `true` or `1`, no further
-helpers will be consulted, nor will the user be prompted (if no
-credential has been provided, the operation will then fail).
-
-For a `store` or `erase` operation, the helper's output is ignored.
-If it fails to perform the requested operation, it may complain to
-stderr to inform the user. If it does not support the requested
-operation (e.g., a read-only store), it should silently ignore the
-request.
-
-If a helper receives any other operation, it should silently ignore the
-request. This leaves room for future operations to be added (older
-helpers will just ignore the new requests).
-
-See also
---------
-
-linkgit:gitcredentials[7]
-
-linkgit:git-config[1] (See configuration variables `credential.*`)
diff --git a/credential.h b/credential.h
index 6b0cd16be2..7f88412346 100644
--- a/credential.h
+++ b/credential.h
@@ -3,8 +3,208 @@
 
 #include "string-list.h"
 
+/**
+ * The credentials API provides an abstracted way of gathering username and
+ * password credentials from the user.
+ *
+ * Typical setup
+ * -------------
+ *
+ * ------------
+ * +-----------------------+
+ * | Git code (C)          |--- to server requiring --->
+ * |                       |        authentication
+ * |.......................|
+ * | C credential API      |--- prompt ---> User
+ * +-----------------------+
+ * 	^      |
+ * 	| pipe |
+ * 	|      v
+ * +-----------------------+
+ * | Git credential helper |
+ * +-----------------------+
+ * ------------
+ *
+ * The Git code (typically a remote-helper) will call the C API to obtain
+ * credential data like a login/password pair (credential_fill). The
+ * API will itself call a remote helper (e.g. "git credential-cache" or
+ * "git credential-store") that may retrieve credential data from a
+ * store. If the credential helper cannot find the information, the C API
+ * will prompt the user. Then, the caller of the API takes care of
+ * contacting the server, and does the actual authentication.
+ *
+ * C API
+ * -----
+ *
+ * The credential C API is meant to be called by Git code which needs to
+ * acquire or store a credential. It is centered around an object
+ * representing a single credential and provides three basic operations:
+ * fill (acquire credentials by calling helpers and/or prompting the user),
+ * approve (mark a credential as successfully used so that it can be stored
+ * for later use), and reject (mark a credential as unsuccessful so that it
+ * can be erased from any persistent storage).
+ *
+ * Example
+ * ~~~~~~~
+ *
+ * The example below shows how the functions of the credential API could be
+ * used to login to a fictitious "foo" service on a remote host:
+ *
+ * -----------------------------------------------------------------------
+ * int foo_login(struct foo_connection *f)
+ * {
+ * 	int status;
+ * 	// Create a credential with some context; we don't yet know the
+ * 	// username or password.
+ *
+ * struct credential c = CREDENTIAL_INIT;
+ * c.protocol = xstrdup("foo");
+ * c.host = xstrdup(f->hostname);
+ *
+ * // Fill in the username and password fields by contacting
+ * // helpers and/or asking the user. The function will die if it
+ * // fails.
+ * credential_fill(&c);
+ *
+ * // Otherwise, we have a username and password. Try to use it.
+ *
+ * status = send_foo_login(f, c.username, c.password);
+ * switch (status) {
+ * case FOO_OK:
+ * // It worked. Store the credential for later use.
+ * credential_accept(&c);
+ * break;
+ * case FOO_BAD_LOGIN:
+ * // Erase the credential from storage so we don't try it again.
+ * credential_reject(&c);
+ * break;
+ * default:
+ * // Some other error occurred. We don't know if the
+ * // credential is good or bad, so report nothing to the
+ * // credential subsystem.
+ * }
+ *
+ * // Free any associated resources.
+ * credential_clear(&c);
+ *
+ * return status;
+ * }
+ * -----------------------------------------------------------------------
+ *
+ * Credential Helpers
+ * ------------------
+ *
+ * Credential helpers are programs executed by Git to fetch or save
+ * credentials from and to long-term storage (where "long-term" is simply
+ * longer than a single Git process; e.g., credentials may be stored
+ * in-memory for a few minutes, or indefinitely on disk).
+ *
+ * Each helper is specified by a single string in the configuration
+ * variable `credential.helper` (and others, see Documentation/git-config.txt).
+ * The string is transformed by Git into a command to be executed using
+ * these rules:
+ *
+ *   1. If the helper string begins with "!", it is considered a shell
+ *      snippet, and everything after the "!" becomes the command.
+ *
+ *   2. Otherwise, if the helper string begins with an absolute path, the
+ *      verbatim helper string becomes the command.
+ *
+ *   3. Otherwise, the string "git credential-" is prepended to the helper
+ *      string, and the result becomes the command.
+ *
+ * The resulting command then has an "operation" argument appended to it
+ * (see below for details), and the result is executed by the shell.
+ *
+ * Here are some example specifications:
+ *
+ * ----------------------------------------------------
+ * # run "git credential-foo"
+ * foo
+ *
+ * # same as above, but pass an argument to the helper
+ * foo --bar=baz
+ *
+ * # the arguments are parsed by the shell, so use shell
+ * # quoting if necessary
+ * foo --bar="whitespace arg"
+ *
+ * # you can also use an absolute path, which will not use the git wrapper
+ * /path/to/my/helper --with-arguments
+ *
+ * # or you can specify your own shell snippet
+ * !f() { echo "password=`cat $HOME/.secret`"; }; f
+ * ----------------------------------------------------
+ *
+ * Generally speaking, rule (3) above is the simplest for users to specify.
+ * Authors of credential helpers should make an effort to assist their
+ * users by naming their program "git-credential-$NAME", and putting it in
+ * the $PATH or $GIT_EXEC_PATH during installation, which will allow a user
+ * to enable it with `git config credential.helper $NAME`.
+ *
+ * When a helper is executed, it will have one "operation" argument
+ * appended to its command line, which is one of:
+ *
+ * `get`::
+ *
+ * 	Return a matching credential, if any exists.
+ *
+ * `store`::
+ *
+ * 	Store the credential, if applicable to the helper.
+ *
+ * `erase`::
+ *
+ * 	Remove a matching credential, if any, from the helper's storage.
+ *
+ * The details of the credential will be provided on the helper's stdin
+ * stream. The exact format is the same as the input/output format of the
+ * `git credential` plumbing command (see the section `INPUT/OUTPUT
+ * FORMAT` in Documentation/git-credential.txt for a detailed specification).
+ *
+ * For a `get` operation, the helper should produce a list of attributes
+ * on stdout in the same format. A helper is free to produce a subset, or
+ * even no values at all if it has nothing useful to provide. Any provided
+ * attributes will overwrite those already known about by Git.  If a helper
+ * outputs a `quit` attribute with a value of `true` or `1`, no further
+ * helpers will be consulted, nor will the user be prompted (if no
+ * credential has been provided, the operation will then fail).
+ *
+ * For a `store` or `erase` operation, the helper's output is ignored.
+ * If it fails to perform the requested operation, it may complain to
+ * stderr to inform the user. If it does not support the requested
+ * operation (e.g., a read-only store), it should silently ignore the
+ * request.
+ *
+ * If a helper receives any other operation, it should silently ignore the
+ * request. This leaves room for future operations to be added (older
+ * helpers will just ignore the new requests).
+ *
+ */
+
+
+/**
+ * This struct represents a single username/password combination
+ * along with any associated context. All string fields should be
+ * heap-allocated (or NULL if they are not known or not applicable).
+ * The meaning of the individual context fields is the same as
+ * their counterparts in the helper protocol.
+ *
+ * This struct should always be initialized with `CREDENTIAL_INIT` or
+ * `credential_init`.
+ */
 struct credential {
+
+    /**
+     * A `string_list` of helpers. Each string specifies an external
+     * helper which will be run, in order, to either acquire or store
+     * credentials. This list is filled-in by the API functions
+     * according to the corresponding configuration variables before
+     * consulting helpers, so there usually is no need for a caller to
+     * modify the helpers field at all.
+     */
 	struct string_list helpers;
+
 	unsigned approved:1,
 		 configured:1,
 		 quit:1,
@@ -19,16 +219,52 @@ struct credential {
 
 #define CREDENTIAL_INIT { STRING_LIST_INIT_DUP }
 
+/* Initialize a credential structure, setting all fields to empty. */
 void credential_init(struct credential *);
+
+/**
+ * Free any resources associated with the credential structure, returning
+ * it to a pristine initialized state.
+ */
 void credential_clear(struct credential *);
 
+/**
+ * Instruct the credential subsystem to fill the username and
+ * password fields of the passed credential struct by first
+ * consulting helpers, then asking the user. After this function
+ * returns, the username and password fields of the credential are
+ * guaranteed to be non-NULL. If an error occurs, the function will
+ * die().
+ */
 void credential_fill(struct credential *);
+
+/**
+ * Inform the credential subsystem that the provided credentials
+ * were successfully used for authentication.  This will cause the
+ * credential subsystem to notify any helpers of the approval, so
+ * that they may store the result to be used again.  Any errors
+ * from helpers are ignored.
+ */
 void credential_approve(struct credential *);
+
+/**
+ * Inform the credential subsystem that the provided credentials
+ * have been rejected. This will cause the credential subsystem to
+ * notify any helpers of the rejection (which allows them, for
+ * example, to purge the invalid credentials from storage). It
+ * will also free() the username and password fields of the
+ * credential and set them to NULL (readying the credential for
+ * another call to `credential_fill`). Any errors from helpers are
+ * ignored.
+ */
 void credential_reject(struct credential *);
 
 int credential_read(struct credential *, FILE *);
 void credential_write(const struct credential *, FILE *);
+
+/* Parse a URL into broken-down credential fields. */
 void credential_from_url(struct credential *, const char *url);
+
 int credential_match(const struct credential *have,
 		     const struct credential *want);
 
