diff --git a/crates/re_data_source/src/data_loader/loader_external.rs b/crates/re_data_source/src/data_loader/loader_external.rs
index a8aa304eeb64..20c9903b1c65 100644
--- a/crates/re_data_source/src/data_loader/loader_external.rs
+++ b/crates/re_data_source/src/data_loader/loader_external.rs
@@ -62,11 +62,14 @@ pub fn iter_external_loaders() -> impl ExactSizeIterator<Item = std::path::PathB
 // ---
 
 /// A [`crate::DataLoader`] that forwards the path to load to all executables present in
-/// the user's `PATH` with a name that starts with `EXTERNAL_DATA_LOADER_PREFIX`.
+/// the user's `PATH` with a name that starts with [`EXTERNAL_DATA_LOADER_PREFIX`].
 ///
 /// The external loaders are expected to log rrd data to their standard output.
 ///
 /// Refer to our `external_data_loader` example for more information.
+///
+/// Checkout our [guide](https://www.rerun.io/docs/howto/open-any-file?speculative-link) on
+/// how to implement external loaders.
 pub struct ExternalLoader;
 
 impl crate::DataLoader for ExternalLoader {
diff --git a/crates/re_data_source/src/data_loader/mod.rs b/crates/re_data_source/src/data_loader/mod.rs
index 4c3c0ae09f6a..973a85c5a5fa 100644
--- a/crates/re_data_source/src/data_loader/mod.rs
+++ b/crates/re_data_source/src/data_loader/mod.rs
@@ -33,14 +33,21 @@ use re_log_types::{ArrowMsg, DataRow, LogMsg};
 ///
 /// ## Registering custom loaders
 ///
-/// TODO(cmc): web guide in upcoming PR
+/// Checkout our [guide](https://www.rerun.io/docs/howto/open-any-file?speculative-link).
 ///
 /// ## Execution
 ///
-/// **All** registered [`DataLoader`]s get called when a user tries to open a file, unconditionally.
+/// **All** known [`DataLoader`]s get called when a user tries to open a file, unconditionally.
 /// This gives [`DataLoader`]s maximum flexibility to decide what files they are interested in, as
 /// opposed to e.g. only being able to look at files' extensions.
 ///
+/// If a [`DataLoader`] has no interest in the given file, it should fail as soon as possible
+/// with a [`DataLoaderError::Incompatible`] error.
+///
+/// Iff all [`DataLoader`]s (including custom and external ones) return with a [`DataLoaderError::Incompatible`]
+/// error, the Viewer will show an error message to the user indicating that the file type is not
+/// supported.
+///
 /// On native, [`DataLoader`]s are executed in parallel.
 ///
 /// [Rerun files]: crate::SUPPORTED_RERUN_EXTENSIONS
@@ -78,8 +85,8 @@ pub trait DataLoader: Send + Sync {
     /// possible (e.g. didn't even manage to open the file).
     /// Otherwise, they should log errors that happen in an asynchronous context.
     ///
-    /// If a [`DataLoader`] has no interest in the given file, it should successfully return
-    /// without pushing any data into `tx`.
+    /// If a [`DataLoader`] has no interest in the given file, it should fail as soon as possible
+    /// with a [`DataLoaderError::Incompatible`] error.
     #[cfg(not(target_arch = "wasm32"))]
     fn load_from_path(
         &self,
@@ -111,8 +118,8 @@ pub trait DataLoader: Send + Sync {
     /// possible (e.g. didn't even manage to open the file).
     /// Otherwise, they should log errors that happen in an asynchronous context.
     ///
-    /// If a [`DataLoader`] has no interest in the given file, it should successfully return
-    /// without pushing any data into `tx`.
+    /// If a [`DataLoader`] has no interest in the given file, it should fail as soon as possible
+    /// with a [`DataLoaderError::Incompatible`] error.
     fn load_from_file_contents(
         &self,
         store_id: re_log_types::StoreId,
diff --git a/docs/content/getting-started/installing-viewer.md b/docs/content/getting-started/installing-viewer.md
index ceb8f3fac1d5..0105f33008b5 100644
--- a/docs/content/getting-started/installing-viewer.md
+++ b/docs/content/getting-started/installing-viewer.md
@@ -1,6 +1,6 @@
 ---
 title: Installing the Rerun Viewer
-order: 0
+order: -1
 ---
 
 The [Rerun Viewer](../reference/viewer/overview.md) can be installed independent of the SDK language you're using.
@@ -20,6 +20,7 @@ In any case you should be able to run `rerun` afterwards to start the Viewer.
 You'll be welcomed by an overview page that allows you to jump into some examples.
 If you're facing any difficulties, don't hesitate to [open an issue](https://github.com/rerun-io/rerun/issues/new/choose) or [join the Discord server](https://discord.gg/PXtCgFBSmH).
 
+The Rerun Viewer has built-in support for opening many kinds of files, and can be [extended to open any other file type](../howto/open-any-file.md) without needing to modify the Rerun codebase itself.
 
 To start getting your own data logged & visualized in the viewer check one of the respective getting started guides:
 * [Python](python.md)
diff --git a/docs/content/howto/open-any-file.md b/docs/content/howto/open-any-file.md
new file mode 100644
index 000000000000..31d6565137d1
--- /dev/null
+++ b/docs/content/howto/open-any-file.md
@@ -0,0 +1,62 @@
+---
+title: Open any file
+order: -10
+---
+
+The Rerun Viewer has built-in support for opening many kinds of files, and can be extended to open any other file type without needing to modify the Rerun codebase itself.
+
+The viewer can load files in 3 different ways:
+- via CLI arguments (e.g. `rerun myfile.jpeg`),
+- using drag-and-drop,
+- using the open dialog in the Rerun Viewer.
+
+All these file loading methods support loading a single file, many files at once (e.g. `rerun myfiles/*`), or even folders.
+
+⚠ Drag-and-drop of folders does [not yet work](https://github.com/rerun-io/rerun/issues/4528) on the web version of the Rerun Viewer ⚠
+
+The following file types have built-in support in the Rerun Viewer:
+- Native Rerun files: `rrd`
+- 3D models: `gltf`, `glb`, `obj`
+- Images: `avif`, `bmp`, `dds`, `exr`, `farbfeld`, `ff`, `gif`, `hdr`, `ico`, `jpeg`, `jpg`, `pam`, `pbm`, `pgm`, `png`, `ppm`, `tga`, `tif`, `tiff`, `webp`.
+- Point clouds: `ply`.
+- Text files: `md`, `txt`.
+
+With the exception of `rrd` files that can be streamed from an HTTP URL (e.g. `rerun https://demo.rerun.io/version/latest/examples/dna/data.rrd`), we only support loading files from the local filesystem for now, with [plans to make this generic over any URI and protocol in the future](https://github.com/rerun-io/rerun/issues/4525).
+
+## Adding support for arbitrary filetypes
+
+Internally, the [`DataLoader`](https://docs.rs/re_data_source/latest/re_data_source/trait.DataLoader.html?speculative-link) trait takes care of loading files into the Viewer.
+
+There are 3 broad kinds of `DataLoader`s: _builtin_, _external_ and _custom_.
+_External_ and _custom_ are the two ways of extending the file loading system that we'll describe below.
+
+When a user attempts to open a file in the Viewer, **all** known `DataLoader`s are notified of the path to be opened, unconditionally.
+This gives `DataLoader`s maximum flexibility to decide what files they are interested in, as opposed to e.g. only being able to look at a file's extension.
+
+Once notified, a `DataLoader` can return a [`DataLoaderError::Incompatible`](https://docs.rs/re_data_source/latest/re_data_source/enum.DataLoaderError.html?speculative-link#variant.Incompatible) error to indicate that it doesn't support a given file type.
+If, and only if, all loaders known to the Viewer return an `Incompatible` error code, then an error message is shown to the user indicating that this file type is not (_yet_) supported.
+
+In these instances of unsupported files, we expose two ways of implementing and registering your `DataLoader`s, explained below.
+
+### External data-loaders
+
+The easiest way to create your own `DataLoader` is by implementing what we call an "external loader": a stand alone executable written in any language that the Rerun SDK ships for. Any executable on your `$PATH` with a name that starts with `rerun-loader-` will be treated as a `DataLoader`.
+
+This executable takes a file path as input on `stdin` and outputs Rerun logs on `stdout`.
+It will be called by the Rerun Viewer when the user opens a file, and be passed the path to that file.
+From there, it can log data as usual, using the [`stdout` logging sink](../reference/sdk-operating-modes?speculative-link#standard-inputoutput).
+
+The Rerun Viewer will then automatically load the data streamed to the external loader's standard output.
+
+Like any other `DataLoader`, an external loader will be notified of all file openings, unconditionally.
+To indicate that it does not support a given file, the loader has to exit with a [dedicated status code](https://docs.rs/rerun/latest/rerun/constant.EXTERNAL_DATA_LOADER_INCOMPATIBLE_EXIT_CODE.html?speculative-link).
+
+Check out our examples for [C++](https://github.com/rerun-io/rerun/tree/main/examples/cpp/external_data_loader), [Python](https://github.com/rerun-io/rerun/tree/main/examples/python/external_data_loader) and [Rust](https://github.com/rerun-io/rerun/tree/main/examples/rust/external_data_loader) that cover every steps in details.
+
+### Custom data-loaders
+
+Another Rust-specific approach is to implement the `DataLoader` trait yourself and register it in the Rerun Viewer.
+
+To do so, you'll need to import `rerun` as a library, register your `DataLoader` and then start the viewer from code.
+
+Check out our [example](https://github.com/rerun-io/rerun/tree/main/examples/rust/custom_data_loader) that cover all these steps in details.
diff --git a/docs/cspell.json b/docs/cspell.json
index 510b3b67d6e1..79a80f377edb 100644
--- a/docs/cspell.json
+++ b/docs/cspell.json
@@ -8,34 +8,137 @@
   ],
   "ignoreWords": [
     "-useb",
+    "Angjoo",
+    "Ankush",
+    "Aubry",
+    "Automagic",
+    "Aytar",
+    "Ayush",
+    "Bazel",
+    "Bgra",
+    "Bhat",
+    "Birkl",
+    "COLMAP",
+    "CSRT",
+    "CVPR",
+    "Carreira",
+    "Chao",
+    "Clément",
+    "Colab",
+    "DCMAKE",
+    "DRERUN",
+    "Dhariwal",
+    "Dilara",
+    "Doersch",
+    "Dollár",
+    "Doxygen",
+    "Dvad",
+    "Efros",
+    "Eigen",
+    "Farooq",
+    "Feichtenhofer",
+    "Firman",
+    "GLES",
+    "Georgios",
+    "Girshick",
+    "Gkioxari",
+    "Gokay",
+    "Gustafson",
+    "Hanzi",
+    "Hawksbill",
+    "Heewoo",
+    "Huggingface",
+    "Jitendra",
+    "Joao",
+    "Kirillov",
+    "LIMAP",
+    "Landmarker",
+    "Larsson",
+    "Malik",
+    "Mathieu",
+    "Mintun",
+    "Mishkin",
+    "Monnier",
+    "Müller",
+    "Niantic",
+    "Nichol",
+    "Nikhila",
+    "Objectron",
+    "Odometry",
+    "Optimus",
+    "PHALP",
+    "Pautrat",
+    "Pavlakos",
+    "Piotr",
+    "Pollefeys",
+    "Prafulla",
+    "Premultiply",
+    "Prisacariu",
+    "Pythonic",
+    "RGBA",
+    "RGBD",
+    "Ravi",
+    "Readback",
+    "Rebatch",
+    "Reiner",
+    "Robo",
+    "Rémi",
+    "SCCACHE",
+    "SLAHMR",
+    "SMPL",
+    "Sayed",
+    "Shaohui",
+    "Shap",
+    "Shariq",
+    "Sitzmann",
+    "Sjouks",
+    "Sonoma",
+    "Struct",
+    "TUID",
+    "TURTLEBOT",
+    "Tete",
+    "Tewari",
+    "Tpng",
+    "Trimesh",
+    "UI's",
+    "URDF",
+    "Unorm",
+    "Vecerik",
+    "Viktor",
+    "WASI",
+    "WINIT",
+    "Wofk",
+    "Wonka",
+    "XCYCW2H2",
+    "XCYCWH",
+    "XYWH",
+    "XYXY",
+    "Xiao",
+    "YXHW",
+    "YXYX",
+    "Yifan",
+    "Yilun",
+    "Yusuf",
+    "Zisserman",
     "aarch",
     "abey",
     "adrr",
     "adwaita",
     "ahash",
     "andreas",
-    "Angjoo",
-    "Ankush",
     "arkit",
     "arkitscene",
     "arkitscenes",
     "arrowified",
     "artefacts",
     "astype",
-    "Aubry",
     "authkey",
     "autogen'd",
-    "Automagic",
     "automations",
     "autoplay",
-    "Aytar",
-    "Ayush",
     "backbuffer",
     "backprojection",
     "barebone",
-    "Bazel",
-    "Bgra",
-    "Bhat",
     "bindgen",
     "bindgroup",
     "binsearch",
@@ -43,20 +146,14 @@
     "binsearching",
     "binstall",
     "binutils",
-    "Birkl",
     "braindump",
     "bringup",
     "callstack",
     "callstacks",
     "camino",
-    "Carreira",
-    "Chao",
     "chrono",
-    "Clément",
     "clippy",
     "codegen",
-    "Colab",
-    "COLMAP",
     "colormap",
     "colormapping",
     "colormaps",
@@ -66,77 +163,53 @@
     "constexpr",
     "consts",
     "controlnet",
-    "CSRT",
     "customizability",
-    "CVPR",
     "dangush",
     "dataclass",
     "dataframe",
     "datastructures",
     "datatypes",
-    "DCMAKE",
     "deallocate",
     "deallocation",
     "debuginfo",
     "dedup",
     "depgraph",
     "devel",
-    "Dhariwal",
     "dicom",
-    "Dilara",
     "docstring",
     "docstrings",
-    "Doersch",
-    "Dollár",
     "dont",
     "downscaled",
     "downscaling",
-    "Doxygen",
     "drawables",
-    "DRERUN",
     "dtype",
     "dtypes",
-    "Dvad",
     "dylib",
     "eframe",
-    "Efros",
     "egui",
     "ehttp",
-    "Eigen",
     "emilk",
     "endcond",
     "enumflags",
     "everytime",
     "ewebsock",
     "extrinsics",
-    "Farooq",
-    "Feichtenhofer",
+    "farbfeld",
     "fieldname",
-    "Firman",
     "flamegraphs",
     "flatbuffers",
     "fname",
     "frontmatter",
     "gcloud",
-    "Georgios",
-    "Girshick",
-    "Gkioxari",
     "glb",
-    "GLES",
     "gltf",
-    "Gokay",
     "grayscale",
     "groupby",
     "gsutil",
-    "Gustafson",
-    "Hanzi",
     "hasher",
-    "Hawksbill",
-    "Heewoo",
     "hickups",
     "howto",
     "hstack",
-    "Huggingface",
     "icosphere",
     "imgmsg",
     "impls",
@@ -145,18 +218,13 @@
     "ipynb",
     "ipython",
     "itertools",
-    "Jitendra",
     "jleibs",
-    "Joao",
     "jparismorgan",
     "justfile",
     "keypoint",
     "keypointid",
     "keypoints",
-    "Kirillov",
     "kpreid",
-    "Landmarker",
-    "Larsson",
     "lavapipe",
     "lerp",
     "libatk",
@@ -169,7 +237,6 @@
     "libvulkan",
     "libxcb",
     "libxkbcommon",
-    "LIMAP",
     "linalg",
     "linestrip",
     "linestrips",
@@ -179,8 +246,6 @@
     "loggable",
     "logtype",
     "mainpage",
-    "Malik",
-    "Mathieu",
     "maturin",
     "mediapipe",
     "meshgrid",
@@ -189,27 +254,22 @@
     "microbatches",
     "microbatching",
     "mimalloc",
-    "Mintun",
-    "Mishkin",
     "mkdocs",
     "mklink",
-    "Monnier",
     "mosphere",
     "mpizenberg",
     "msvc",
-    "Müller",
     "multimodal",
     "multiview",
     "mydata",
+    "myfile",
+    "myfiles",
     "mypy",
     "nanos",
     "nans",
     "nbconvert",
     "ncipollo",
     "ndarray",
-    "Niantic",
-    "Nichol",
-    "Nikhila",
     "nohash",
     "noqa",
     "nuScenes",
@@ -217,29 +277,18 @@
     "nyud",
     "obbs",
     "obj",
-    "Objectron",
     "odometry",
-    "Odometry",
     "omahs",
-    "Optimus",
     "pablovela",
     "pacman",
     "parametrizations",
     "patchelf",
     "pathlib",
-    "Pautrat",
-    "Pavlakos",
-    "PHALP",
     "photogrammetrically",
-    "Piotr",
     "pixi",
     "pngcrush",
     "pointcloud",
-    "Pollefeys",
-    "Prafulla",
-    "Premultiply",
     "prettyplease",
-    "Prisacariu",
     "proto",
     "protoc",
     "pycollada",
@@ -247,32 +296,23 @@
     "pypi",
     "pyright",
     "pytest",
-    "Pythonic",
     "quickstart",
     "randn",
     "randr",
     "rasterizer",
-    "Ravi",
     "readback",
-    "Readback",
     "realsense",
-    "Rebatch",
     "rebatching",
     "recognised",
     "rects",
     "refcount",
     "refcounted",
-    "Reiner",
-    "Rémi",
     "renamings",
     "repr",
     "reproj",
     "reqwest",
-    "RGBA",
     "rgbd",
-    "RGBD",
     "roadmap",
-    "Robo",
     "rosclpy",
     "roundtrip",
     "roundtrips",
@@ -284,9 +324,7 @@
     "rustsec",
     "rustup",
     "rviz",
-    "Sayed",
     "sccache",
-    "SCCACHE",
     "scipy",
     "screeshot",
     "scrollwheel",
@@ -295,15 +333,7 @@
     "serde",
     "serialisation",
     "serialised",
-    "Shaohui",
-    "Shap",
-    "Shariq",
-    "Sitzmann",
-    "Sjouks",
-    "SLAHMR",
     "smallvec",
-    "SMPL",
-    "Sonoma",
     "spaceview",
     "spaceviews",
     "spammy",
@@ -312,79 +342,53 @@
     "startswith",
     "staticmethod",
     "struct",
-    "Struct",
     "structs",
     "subdir",
     "superquadrics",
     "tableofcontents",
     "taplo",
-    "Tete",
-    "Tewari",
     "thiserror",
     "timepanel",
     "timepoint",
     "timepoints",
     "timeseries",
     "tinyvec",
-    "Tpng",
     "trackpad",
     "trimesh",
-    "Trimesh",
     "trimleft", // doxygen command
-    "TUID",
     "turtlebot",
-    "TURTLEBOT",
-    "UI's",
     "unmultiplied",
-    "Unorm",
     "upcasting",
     "upsampling",
     "upvote",
     "urdf",
-    "URDF",
     "ureq",
     "urholaukkarinen",
     "urlparse",
     "usecases",
     "usize",
-    "Vecerik",
     "venv",
-    "Viktor",
     "virtualenv",
     "vstack",
     "vsuryamurthy",
     "vulkan",
     "walkthrough",
-    "WASI",
     "webgl",
     "webgpu",
     "webm",
+    "webp",
     "webpki",
     "werror",
     "wgpu",
     "wgsl",
     "whele",
-    "WINIT",
-    "Wofk",
-    "Wonka",
     "wxyz",
-    "XCYCW2H2",
-    "XCYCWH",
     "xfixes",
-    "Xiao",
     "xtask",
-    "XYWH",
-    "XYXY",
     "xyzw",
-    "Yifan",
-    "Yilun",
     "yourdfpy",
     "yourname",
-    "Yusuf",
-    "YXHW",
-    "YXYX",
     "zipfile",
-    "Zisserman",
     "zrezke",
     "zstd",
     "zune"
diff --git a/examples/cpp/external_data_loader/main.cpp b/examples/cpp/external_data_loader/main.cpp
index 24b538a0bf71..adddc44269c2 100644
--- a/examples/cpp/external_data_loader/main.cpp
+++ b/examples/cpp/external_data_loader/main.cpp
@@ -7,9 +7,14 @@
 
 static const char* USAGE = R"(
 This is an example executable data-loader plugin for the Rerun Viewer.
+Any executable on your `$PATH` with a name that starts with `rerun-loader-` will be treated as an
+external data-loader.
 
-It will log C++ source code files as markdown documents.
-To try it out, compile it and place it in your $PATH, then open a C++ source file with Rerun (`rerun file.cpp`).
+This particular one will log C++ source code files as markdown documents, and return a
+special exit code to indicate that it doesn't support anything else.
+
+To try it out, compile it and place it in your $PATH as `rerun-loader-cpp-file`, then open a C++ source
+file with Rerun (`rerun file.cpp`).
 
 USAGE:
   rerun-loader-cpp-file [OPTIONS] FILEPATH
diff --git a/examples/python/external_data_loader/main.py b/examples/python/external_data_loader/main.py
index 1ddb5d7d78bc..f052321923db 100755
--- a/examples/python/external_data_loader/main.py
+++ b/examples/python/external_data_loader/main.py
@@ -17,9 +17,14 @@
 parser = argparse.ArgumentParser(
     description="""
 This is an example executable data-loader plugin for the Rerun Viewer.
+Any executable on your `$PATH` with a name that starts with `rerun-loader-` will be
+treated as an external data-loader.
 
-It will log Python source code files as markdown documents.
-To try it out, copy it in your $PATH as `rerun-loader-python-file`, then open a Python source file with Rerun (`rerun file.py`).
+This particular one will log Python source code files as markdown documents, and return a
+special exit code to indicate that it doesn't support anything else.
+
+To try it out, copy it in your $PATH as `rerun-loader-python-file`, then open a Python source
+file with Rerun (`rerun file.py`).
 """
 )
 parser.add_argument("filepath", type=str)
diff --git a/examples/rust/external_data_loader/src/main.rs b/examples/rust/external_data_loader/src/main.rs
index 2afebc073440..45bb7b4e7a8a 100644
--- a/examples/rust/external_data_loader/src/main.rs
+++ b/examples/rust/external_data_loader/src/main.rs
@@ -13,10 +13,16 @@ use rerun::{
 // that file, otherwise you can just create a dedicated recording for it. Or both.
 
 /// This is an example executable data-loader plugin for the Rerun Viewer.
+/// Any executable on your `$PATH` with a name that starts with [`rerun-loader-`] will be
+/// treated as an external data-loader.
 ///
-/// It will log Rust source code files as markdown documents.
-/// To try it out, install it in your $PATH (`cargo install --path . -f`), then open
+/// This particular one will log Rust source code files as markdown documents, and return a
+/// special exit code to indicate that it doesn't support anything else.
+///
+/// To try it out, install it in your $PATH (`cargo install --path . -f`), then open a
 /// Rust source file with Rerun (`rerun file.rs`).
+///
+/// [`rerun-loader-`]: `rerun::EXTERNAL_DATA_LOADER_PREFIX`
 #[derive(argh::FromArgs)]
 struct Args {
     #[argh(positional)]