diff --git a/docs/functions/core/memory/why2_fdopen.md b/docs/functions/core/memory/why2_fdopen.md
new file mode 100644
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@@ -0,0 +1,38 @@
+<!--
+This is part of WHY2
+Copyright (C) 2022 Václav Šmejkal
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+-->
+
+# why2_fdopen
+
+## Parameters
+
+| Identifier | Data type |
+| ---------- | --------- |
+| `file`     | `int`     |
+| `modes`    | `char *`  |
+
+## Attributes
+
+|                     |                                                |
+| ------------------  | ---------------------------------------------- |
+| **Return type**     | `void *`                                       |
+| **Header comment**  | *This functions doesn't have any description.* |
+| **Added in commit** | [`1285f52b6737093f802163b3dc313253ea96f5bc`](https://github.com/ENGO150/WHY2/commit/1285f52b6737093f802163b3dc313253ea96f5bc) |
+
+## Description
+
+Function passes `file` and `modes` into [`fdopen`](https://linux.die.net/man/3/fdopen) function and returns the output value. The value is also pushed to [`linked-list`](../../../../types/core/llist/why2_list_t) for garbage collector.
\ No newline at end of file
diff --git a/docs/functions/index.md b/docs/functions/index.md
index 92c81e9..1313015 100644
--- a/docs/functions/index.md
+++ b/docs/functions/index.md
@@ -95,6 +95,7 @@ You can find documentation for every *public* function of WHY2 below.
 | [`why2_recalloc`](./core/memory/why2_recalloc) | Same as why2_realloc but fills the pointer with null-terms |
 | [`why2_strdup`](./core/memory/why2_strdup)     | *This functions doesn't have any description.*             |
 | [`why2_fopen`](./core/memory/why2_fopen)       | *This functions doesn't have any description.*             |
+| [`why2_fdopen`](./core/memory/why2_fdopen)     | *This functions doesn't have any description.*             |
 
 ## Logger