diff --git a/.gitignore b/.gitignore
index 66fd13c90..62b493e6a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -13,3 +13,5 @@
 
 # Dependency directories (remove the comment below to include it)
 # vendor/
+
+.DS_Store
diff --git a/diagrams/message.mmd b/diagrams/message.mmd
new file mode 100644
index 000000000..36aae4bd3
--- /dev/null
+++ b/diagrams/message.mmd
@@ -0,0 +1,12 @@
+sequenceDiagram
+  participant Alice
+  participant App A
+  participant Server A
+  participant Server B
+  participant App B
+  participant Bob
+  Alice ->> App A: Alice writes the message to Bob in the app
+  App A ->> Server A: the message (including ID & timestamp) is encrypted by <Alice-Bob public key> and sent to all Alice's servers<br>{from: <Bob-Alice key hash>, to: <Alice-Bob key hash>, message: <encrypted with Alice-Bob public key>}
+  Server A ->> Server B: Alice's servers use <Alice-Bob key hash> to locate Bob's servers<br>and forwards encrypted message to all Bob's servers (in case they are different from Alice's servers
+  Server B ->> App B: Bob's servers send the message to Bob's app
+  App B ->> Bob: Bob's app uses <Bob-Alice key hash> to identify Alice<br>and decrypts the message with <Bob-Alice private key> to show it
\ No newline at end of file
diff --git a/diagrams/message.svg b/diagrams/message.svg
new file mode 100644
index 000000000..c5591f37d
--- /dev/null
+++ b/diagrams/message.svg
@@ -0,0 +1,494 @@
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+
+
+
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+  color: #333; }
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+#mermaid-1576936987542 .label text {
+  fill: #333; }
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+#mermaid-1576936987542 .node circle,
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+  text-align: center; }
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+#mermaid-1576936987542 .node.clickable {
+  cursor: pointer; }
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+  stroke-width: 1.5px; }
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+  stroke-width: 1px; }
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+  padding: 2px;
+  font-family: 'trebuchet ms', verdana, arial;
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+  font-size: 12px;
+  background: #ffffde;
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+  border-radius: 2px;
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+:root { --mermaid-font-family: "trebuchet ms", verdana, arial;}</style><style>#mermaid-1576936987542 {
+    color: rgba(0, 0, 0, 0.65);
+    font: ;
+  }</style><g></g><g><line id="actor5942" x1="75" y1="5" x2="75" y2="325" class="actor-line" stroke-width="0.5px" stroke="#999"></line><rect x="0" y="0" fill="#eaeaea" stroke="#666" width="150" height="65" rx="3" ry="3" class="actor"></rect><text x="75" y="32.5" dominant-baseline="central" alignment-baseline="central" class="actor" style="text-anchor: middle; font-size: 14px;"><tspan x="75" dy="0">Alice</tspan></text></g><g><line id="actor5943" x1="275" y1="5" x2="275" y2="325" class="actor-line" stroke-width="0.5px" stroke="#999"></line><rect x="200" y="0" fill="#eaeaea" stroke="#666" width="150" height="65" rx="3" ry="3" class="actor"></rect><text x="275" y="32.5" dominant-baseline="central" alignment-baseline="central" class="actor" style="text-anchor: middle; font-size: 14px;"><tspan x="275" dy="0">App A</tspan></text></g><g><line id="actor5944" x1="475" y1="5" x2="475" y2="325" class="actor-line" stroke-width="0.5px" stroke="#999"></line><rect x="400" y="0" fill="#eaeaea" stroke="#666" width="150" height="65" rx="3" ry="3" class="actor"></rect><text x="475" y="32.5" dominant-baseline="central" alignment-baseline="central" class="actor" style="text-anchor: middle; font-size: 14px;"><tspan x="475" dy="0">Server A</tspan></text></g><g><line id="actor5945" x1="675" y1="5" x2="675" y2="325" class="actor-line" stroke-width="0.5px" stroke="#999"></line><rect x="600" y="0" fill="#eaeaea" stroke="#666" width="150" height="65" rx="3" ry="3" class="actor"></rect><text x="675" y="32.5" dominant-baseline="central" alignment-baseline="central" class="actor" style="text-anchor: middle; font-size: 14px;"><tspan x="675" dy="0">Server B</tspan></text></g><g><line id="actor5946" x1="875" y1="5" x2="875" y2="325" class="actor-line" stroke-width="0.5px" stroke="#999"></line><rect x="800" y="0" fill="#eaeaea" stroke="#666" width="150" height="65" rx="3" ry="3" class="actor"></rect><text x="875" y="32.5" dominant-baseline="central" alignment-baseline="central" class="actor" style="text-anchor: middle; font-size: 14px;"><tspan x="875" dy="0">App B</tspan></text></g><g><line id="actor5947" x1="1075" y1="5" x2="1075" y2="325" class="actor-line" stroke-width="0.5px" stroke="#999"></line><rect x="1000" y="0" fill="#eaeaea" stroke="#666" width="150" height="65" rx="3" ry="3" class="actor"></rect><text x="1075" y="32.5" dominant-baseline="central" alignment-baseline="central" class="actor" style="text-anchor: middle; font-size: 14px;"><tspan x="1075" dy="0">Bob</tspan></text></g><defs><marker id="arrowhead" refX="5" refY="2" markerWidth="6" markerHeight="4" orient="auto"><path d="M 0,0 V 4 L6,2 Z"></path></marker></defs><defs><marker id="crosshead" markerWidth="15" markerHeight="8" orient="auto" refX="16" refY="4"><path fill="black" stroke="#000000" stroke-width="1px" d="M 9,2 V 6 L16,4 Z" style="stroke-dasharray: 0, 0;"></path><path fill="none" stroke="#000000" stroke-width="1px" d="M 0,1 L 6,7 M 6,1 L 0,7" style="stroke-dasharray: 0, 0;"></path></marker></defs><defs><marker id="sequencenumber" refX="15" refY="15" markerWidth="60" markerHeight="40" orient="auto"><circle cx="15" cy="15" r="6"></circle></marker></defs><g><text x="175" y="93" class="messageText" style="text-anchor: middle;">Alice writes the message to Bob in the app</text><line x1="75" y1="100" x2="275" y2="100" class="messageLine0" stroke-width="2" stroke="black" marker-end="url(#arrowhead)" style="fill: none;"></line></g><g><text x="375" y="128" class="messageText" style="text-anchor: middle;">the message (including ID &amp; timestamp) is encrypted by &lt;Alice-Bob public key&gt; and sent to all Alice's servers</text><text x="375" y="145" class="messageText" style="text-anchor: middle;">{from: &lt;Bob-Alice key hash&gt;, to: &lt;Alice-Bob key hash&gt;, message: &lt;encrypted with Alice-Bob public key&gt;}</text><line x1="275" y1="135" x2="475" y2="135" class="messageLine0" stroke-width="2" stroke="black" marker-end="url(#arrowhead)" style="fill: none;"></line></g><g><text x="575" y="163" class="messageText" style="text-anchor: middle;">Alice's servers use &lt;Alice-Bob key hash&gt; to locate Bob's servers</text><text x="575" y="180" class="messageText" style="text-anchor: middle;">and forwards encrypted message to all Bob's servers (in case they are different from Alice's servers</text><line x1="475" y1="170" x2="675" y2="170" class="messageLine0" stroke-width="2" stroke="black" marker-end="url(#arrowhead)" style="fill: none;"></line></g><g><text x="775" y="198" class="messageText" style="text-anchor: middle;">Bob's servers send the message to Bob's app</text><line x1="675" y1="205" x2="875" y2="205" class="messageLine0" stroke-width="2" stroke="black" marker-end="url(#arrowhead)" style="fill: none;"></line></g><g><text x="975" y="233" class="messageText" style="text-anchor: middle;">Bob's app uses &lt;Bob-Alice key hash&gt; to identify Alice</text><text x="975" y="250" class="messageText" style="text-anchor: middle;">and decrypts the message with &lt;Bob-Alice private key&gt; to show it</text><line x1="875" y1="240" x2="1075" y2="240" class="messageLine0" stroke-width="2" stroke="black" marker-end="url(#arrowhead)" style="fill: none;"></line></g><g><rect x="0" y="260" fill="#eaeaea" stroke="#666" width="150" height="65" rx="3" ry="3" class="actor"></rect><text x="75" y="292.5" dominant-baseline="central" alignment-baseline="central" class="actor" style="text-anchor: middle; font-size: 14px;"><tspan x="75" dy="0">Alice</tspan></text></g><g><rect x="200" y="260" fill="#eaeaea" stroke="#666" width="150" height="65" rx="3" ry="3" class="actor"></rect><text x="275" y="292.5" dominant-baseline="central" alignment-baseline="central" class="actor" style="text-anchor: middle; font-size: 14px;"><tspan x="275" dy="0">App A</tspan></text></g><g><rect x="400" y="260" fill="#eaeaea" stroke="#666" width="150" height="65" rx="3" ry="3" class="actor"></rect><text x="475" y="292.5" dominant-baseline="central" alignment-baseline="central" class="actor" style="text-anchor: middle; font-size: 14px;"><tspan x="475" dy="0">Server A</tspan></text></g><g><rect x="600" y="260" fill="#eaeaea" stroke="#666" width="150" height="65" rx="3" ry="3" class="actor"></rect><text x="675" y="292.5" dominant-baseline="central" alignment-baseline="central" class="actor" style="text-anchor: middle; font-size: 14px;"><tspan x="675" dy="0">Server B</tspan></text></g><g><rect x="800" y="260" fill="#eaeaea" stroke="#666" width="150" height="65" rx="3" ry="3" class="actor"></rect><text x="875" y="292.5" dominant-baseline="central" alignment-baseline="central" class="actor" style="text-anchor: middle; font-size: 14px;"><tspan x="875" dy="0">App B</tspan></text></g><g><rect x="1000" y="260" fill="#eaeaea" stroke="#666" width="150" height="65" rx="3" ry="3" class="actor"></rect><text x="1075" y="292.5" dominant-baseline="central" alignment-baseline="central" class="actor" style="text-anchor: middle; font-size: 14px;"><tspan x="1075" dy="0">Bob</tspan></text></g></svg>
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diff --git a/readme.md b/readme.md
index e6c966b3b..ab34038f2 100644
--- a/readme.md
+++ b/readme.md
@@ -71,4 +71,10 @@ Client apps should provide the following:
   - optionally define the server(s) they trust and will connect to, including the servers that require server key to access.
   - optionally require that connected users connect to one of the servers they trust when sending messages to the user profile.
   - store history of all conversations encrypted using user client app password (or some other device specific encryption mechanism).
-  
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+
+
+## Sequence diagrams
+
+### Sending message
+
+![Sending message](/diagrams/message.svg)
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