diff --git a/README.md b/README.md
index 6147e9fc..e035c11b 100644
--- a/README.md
+++ b/README.md
@@ -19,6 +19,12 @@ Oxigraph is in heavy development and SPARQL query evaluation has not been optimi
 The development roadmap is using [GitHub milestones](https://github.com/oxigraph/oxigraph/milestones?direction=desc&sort=completeness&state=open).
 Oxigraph internal design [is described on the wiki](https://github.com/oxigraph/oxigraph/wiki/Architecture).
 
+Oxigraph implements the following specifications:
+
+- [SPARQL 1.1 Query](https://www.w3.org/TR/sparql11-query/), [SPARQL 1.1 Update](https://www.w3.org/TR/sparql11-update/), and [SPARQL 1.1 Federated Query](https://www.w3.org/TR/sparql11-federated-query/).
+- [Turtle](https://www.w3.org/TR/turtle/), [TriG](https://www.w3.org/TR/trig/), [N-Triples](https://www.w3.org/TR/n-triples/), [N-Quads](https://www.w3.org/TR/n-quads/), and [RDF XML](https://www.w3.org/TR/rdf-syntax-grammar/) RDF serialization formats for both data ingestion and retrieval using the [Rio library](https://github.com/oxigraph/rio).
+- [SPARQL Query Results XML Format](https://www.w3.org/TR/rdf-sparql-XMLres/), [SPARQL 1.1 Query Results JSON Format](https://www.w3.org/TR/sparql11-results-json/) and [SPARQL 1.1 Query Results CSV and TSV Formats](https://www.w3.org/TR/sparql11-results-csv-tsv/).
+
 It is split into multiple parts:
 
 - [The database written as a Rust library](https://crates.io/crates/oxigraph). Its source code is in the `lib` directory.
@@ -31,11 +37,18 @@ It is split into multiple parts:
   Note that it was previously named [Oxigraph server](https://crates.io/crates/oxigraph-server).
   [![Latest Version](https://img.shields.io/crates/v/oxigraph-cli.svg)](https://crates.io/crates/oxigraph-cli)
 
-Oxigraph implements the following specifications:
-
-- [SPARQL 1.1 Query](https://www.w3.org/TR/sparql11-query/), [SPARQL 1.1 Update](https://www.w3.org/TR/sparql11-update/), and [SPARQL 1.1 Federated Query](https://www.w3.org/TR/sparql11-federated-query/).
-- [Turtle](https://www.w3.org/TR/turtle/), [TriG](https://www.w3.org/TR/trig/), [N-Triples](https://www.w3.org/TR/n-triples/), [N-Quads](https://www.w3.org/TR/n-quads/), and [RDF XML](https://www.w3.org/TR/rdf-syntax-grammar/) RDF serialization formats for both data ingestion and retrieval using the [Rio library](https://github.com/oxigraph/rio).
-- [SPARQL Query Results XML Format](https://www.w3.org/TR/rdf-sparql-XMLres/), [SPARQL 1.1 Query Results JSON Format](https://www.w3.org/TR/sparql11-results-json/) and [SPARQL 1.1 Query Results CSV and TSV Formats](https://www.w3.org/TR/sparql11-results-csv-tsv/).
+Also, some parts of Oxigraph are available as standalone Rust crates:
+* [`oxrdf`](https://crates.io/crates/oxrdf), datastructures encoding RDF basic concepts (the [`oxigraph::model`](crate::model) module).
+* [`oxrdfio`](https://crates.io/crates/oxrdfio), a unified parser and serializer API for RDF formats (the [`oxigraph::io`](crate::io) module). It itself relies on:
+  * [`oxttl`](https://crates.io/crates/oxttl), N-Triple, N-Quad, Turtle, TriG and N3 parsing and serialization.
+  * [`oxrdfxml`](https://crates.io/crates/oxrdfxml), RDF/XML parsing and serialization.
+* [`spargebra`](https://crates.io/crates/spargebra), a SPARQL parser.
+* [`sparesults`](https://crates.io/crates/sparesults), parsers and serializers for SPARQL result formats.
+* [`sparopt`](https://crates.io/crates/sparesults), a SPARQL optimizer.
+* [`oxsdatatypes`](https://crates.io/crates/oxsdatatypes), an implementation of some XML Schema datatypes.
+
+The library layers in Oxigraph. The elements above depend on the elements below:
+![Oxigraph libraries architecture diagram](./docs/arch-diagram.svg)
 
 A preliminary benchmark [is provided](bench/README.md). There is also [a document describing Oxigraph technical architecture](https://github.com/oxigraph/oxigraph/wiki/Architecture).
 
diff --git a/docs/arch-diagram.svg b/docs/arch-diagram.svg
new file mode 100644
index 00000000..749c466b
--- /dev/null
+++ b/docs/arch-diagram.svg
@@ -0,0 +1,120 @@
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+    <style>.svgbob line, .svgbob path, .svgbob circle, .svgbob rect, .svgbob polygon {
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+        stroke-opacity: 1;
+        fill-opacity: 1;
+        stroke-linecap: round;
+        stroke-linejoin: miter;
+        }
+        .svgbob text {
+        white-space: pre;
+        fill: black;
+        font-family: Iosevka Fixed, monospace;
+        font-size: 14px;
+        }
+        .svgbob rect.backdrop {
+        stroke: none;
+        fill: white;
+        }
+        .svgbob .broken {
+        stroke-dasharray: 8;
+        }
+        .svgbob .filled {
+        fill: black;
+        }
+        .svgbob .bg_filled {
+        fill: white;
+        stroke-width: 1;
+        }
+        .svgbob .nofill {
+        fill: white;
+        }
+        .svgbob .end_marked_arrow {
+        marker-end: url(#arrow);
+        }
+        .svgbob .start_marked_arrow {
+        marker-start: url(#arrow);
+        }
+        .svgbob .end_marked_diamond {
+        marker-end: url(#diamond);
+        }
+        .svgbob .start_marked_diamond {
+        marker-start: url(#diamond);
+        }
+        .svgbob .end_marked_circle {
+        marker-end: url(#circle);
+        }
+        .svgbob .start_marked_circle {
+        marker-start: url(#circle);
+        }
+        .svgbob .end_marked_open_circle {
+        marker-end: url(#open_circle);
+        }
+        .svgbob .start_marked_open_circle {
+        marker-start: url(#open_circle);
+        }
+        .svgbob .end_marked_big_open_circle {
+        marker-end: url(#big_open_circle);
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+        .svgbob .start_marked_big_open_circle {
+        marker-start: url(#big_open_circle);
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+        fill: papayawhip;
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+        .svgbob .p{
+        fill: lightyellow;
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+        .svgbob .j{
+        fill: lightgreen;
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+    </style>
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+        </marker>
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+    <rect x="244" y="8" width="136" height="32" class="solid nofill p" rx="0"></rect>
+    <text x="258" y="28">pyoxigraph</text>
+    <rect x="468" y="8" width="144" height="32" class="solid nofill j" rx="0"></rect>
+    <text x="482" y="28">oxigraph</text>
+    <text x="554" y="28">JS</text>
+    <rect x="4" y="72" width="608" height="32" class="solid nofill r" rx="0"></rect>
+    <text x="18" y="92">oxigraph</text>
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+    <text x="82" y="156">oxrdfio</text>
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+    <text x="362" y="156">sparopt</text>
+    <rect x="68" y="200" width="96" height="32" class="solid nofill r" rx="0"></rect>
+    <text x="82" y="220">oxttl</text>
+    <rect x="180" y="200" width="120" height="32" class="solid nofill r" rx="0"></rect>
+    <text x="194" y="220">oxrdfxml</text>
+    <rect x="316" y="200" width="144" height="32" class="solid nofill r" rx="0"></rect>
+    <text x="330" y="220">spargebra</text>
+    <rect x="476" y="200" width="136" height="32" class="solid nofill r" rx="0"></rect>
+    <text x="490" y="220">sparesults</text>
+    <rect x="36" y="264" width="576" height="32" class="solid nofill r" rx="0"></rect>
+    <text x="50" y="284">oxrdf</text>
+    <rect x="4" y="328" width="152" height="32" class="solid nofill r" rx="0"></rect>
+    <text x="18" y="348">oxsdatatypes</text>
+</svg>
\ No newline at end of file
diff --git a/docs/arch-diagram.txt b/docs/arch-diagram.txt
new file mode 100644
index 00000000..ff3a5be0
--- /dev/null
+++ b/docs/arch-diagram.txt
@@ -0,0 +1,35 @@
++------------------+          +----------------+          +-----------------+
++ oxigraph CLI {r} +          + pyoxigraph {p} +          + oxigraph JS {j} +
++------------------+          +----------------+          +-----------------+
+
++---------------------------------------------------------------------------+
++ oxigraph (Rust) {r}                                                       +
++---------------------------------------------------------------------------+
+
+        +----------------------------+     +-------------+
+        + oxrdfio {r}                +     + sparopt {r} +
+        +----------------------------+     +-------------+
+
+        +-----------+ +--------------+ +-----------------+ +----------------+
+        + oxttl {r} + + oxrdfxml {r} + + spargebra {r}   + + sparesults {r} +
+        +-----------+ +--------------+ +-----------------+ +----------------+
+
+    +-----------------------------------------------------------------------+
+    + oxrdf {r}                                                             +
+    +-----------------------------------------------------------------------+
+
++------------------+
++ oxsdatatypes {r} +
++------------------+
+
+
+# Legend:
+r = {
+    fill: papayawhip;
+}
+p = {
+    fill: lightyellow;
+}
+j = {
+    fill: lightgreen;
+}