diff --git a/README.md b/README.md
index ed01e21..f7ecb45 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 The MIT-licensed SDK for official [InvoiceShelf](https://invoiceshelf.com) v3 modules. It extends [`nwidart/laravel-modules`](https://github.com/nWidart/laravel-modules) with the contracts used by InvoiceShelf's module host and signed marketplace packages.
 
-SDK **3.5** supports Module API **1.4**. First-party module packages live in their own repositories and are licensed `AGPL-3.0-only`; this SDK remains MIT.
+SDK **3.7** supports Module API **1.6**. First-party module packages live in their own repositories and are licensed `AGPL-3.0-only`; this SDK remains MIT.
 
 ## What a module can add
 
@@ -12,6 +12,7 @@ SDK **3.5** supports Module API **1.4**. First-party module packages live in the
 - Actions, panels, form sections and save hooks on host records (invoices, estimates, customers, payments and more), plus entries in the global New menu.
 - Company abilities contributed to the host's authorization catalogue, so a module can ship its own permissions instead of reusing host ones.
 - Whole invoices to read and structured XML to embed in invoice PDFs (Module API 1.5.0), for modules that produce e-invoices; see [Documents and invoice PDFs](#documents-and-invoice-pdfs).
+- QR codes drawn by the host (Module API 1.6.0), so a module needs no QR library of its own; see [QR codes](#qr-codes).
 - Narrow host contracts under [`src/Contracts/Host`](src/Contracts/Host) for settings, authorization, and read-only company-data queries. `CompanyDataReader` covers the AI assistant's built-in queries plus `companyMembers()` and `existingInvoiceIds()` for modules that assign work to members or stamp their entries against invoices. Module code must not depend on InvoiceShelf Eloquent models.
 - AI drivers through [`src/Ai`](src/Ai): extend `AiDriver`, return `AiChatResponse`, and throw `AiException` for safe, localizable provider failures.
 
@@ -23,8 +24,8 @@ Declare compatibility in `module.json`, then test it against the host versions y
 
 | Concern | Current contract |
 | --- | --- |
-| SDK | `invoiceshelf/modules` `^3.6` |
-| Module API | `^1.3.0`; `^1.4.0` for bundled dependencies and record slots; `^1.5.0` for documents and invoice PDF attachments |
+| SDK | `invoiceshelf/modules` `^3.7` |
+| Module API | `^1.3.0`; `^1.4.0` for bundled dependencies and record slots; `^1.5.0` for documents and invoice PDF attachments; `^1.6.0` for QR codes |
 | Host application | Your explicit InvoiceShelf 3.x range |
 | PHP | The range your module actually supports |
 
@@ -253,6 +254,24 @@ A module that turns invoices into other documents, such as an EN 16931 e-invoice
 
 These are Module API **1.5.0** additions; declare `"module_api": "^1.5.0"` to use them.
 
+### QR codes
+
+Ask the container for `QrCodeGenerator` instead of bundling a QR library:
+
+```php
+use InvoiceShelf\Modules\Contracts\Host\QrCodeGenerator;
+
+$src = app(QrCodeGenerator::class)->svgDataUri($payload, size: 160);
+// <img src="{{ $src }}" alt="" style="width: 40mm; height: 40mm;">
+```
+
+- **`svg()`** returns an SVG document and **`svgDataUri()`** the same as a `data:` URI for an `<img>` in a PDF template or a Blade view. Both PDF drivers draw it without fetching anything, and no image extension is needed on the server.
+- **Content** is UTF-8 text. Plain ASCII is encoded as it is; anything else is encoded as UTF-8 with an ECI marker, which is what EPC (SEPA credit transfer) and Swiss QR-bill payloads expect.
+- **Options:** `$size` is the edge in pixels with the quiet zone included, `$margin` the quiet zone in modules (4 by default, as the QR standard asks), and `ErrorCorrection` ([`src/Qr`](src/Qr)) runs from `Low` to `High`, `Medium` by default, which the payment specifications above require.
+- Content that is empty or too long for a QR code at the chosen level throws `InvalidArgumentException`.
+
+These are Module API **1.6.0** additions; declare `"module_api": "^1.6.0"` to use them.
+
 ### Responsive classes
 
 Your stylesheet is a Tailwind build of its own, loaded next to the host's, and the two share class names: both may define `.hidden` or `.w-full`. Between rules of equal weight the later sheet wins, so the host adds its stylesheet again after the module sheets, and a module can never break the app's layout. The cost lands on your markup: the host's plain utilities win over your breakpoint variants. `hidden sm:flex` stays hidden on desktop unless the host's own build happens to contain `sm:flex` too, and that changes from release to release.
diff --git a/RELEASING.md b/RELEASING.md
index 680a626..f9a46b3 100644
--- a/RELEASING.md
+++ b/RELEASING.md
@@ -18,7 +18,7 @@ An official module normally calls the tagged SDK workflow from its own tag workf
 ```yaml
 jobs:
   release:
-    uses: InvoiceShelf/modules/.github/workflows/module-release.yml@3.6.0
+    uses: InvoiceShelf/modules/.github/workflows/module-release.yml@3.7.0
     with:
       channel: stable
     secrets: inherit
diff --git a/src/Contracts/Host/QrCodeGenerator.php b/src/Contracts/Host/QrCodeGenerator.php
new file mode 100644
index 0000000..b1ee435
--- /dev/null
+++ b/src/Contracts/Host/QrCodeGenerator.php
@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+namespace InvoiceShelf\Modules\Contracts\Host;
+
+use InvalidArgumentException;
+use InvoiceShelf\Modules\Qr\ErrorCorrection;
+
+/**
+ * QR codes drawn by the host, so a module does not bundle a QR library of its
+ * own. Module API 1.6.0.
+ *
+ * Content is UTF-8 text: a URL, or a payment payload such as an EPC or Swiss
+ * QR-bill one. Plain ASCII is encoded byte for byte; anything else is encoded
+ * as UTF-8 with an ECI marker saying so, which is what those payment
+ * specifications expect, rather than being converted to ISO-8859-1.
+ *
+ * The output is SVG, which needs no image extension on the server, stays
+ * sharp at any print size, and is drawn by both of the host's PDF drivers.
+ */
+interface QrCodeGenerator
+{
+    /**
+     * An SVG document of the code.
+     *
+     * @param  int  $size  the edge of the square image in pixels, quiet zone included
+     * @param  int  $margin  the quiet zone around the code, in modules; 4 is what the QR standard asks for
+     *
+     * @throws InvalidArgumentException when the content is empty or too long for a QR code at that level
+     */
+    public function svg(
+        string $content,
+        int $size = 200,
+        ErrorCorrection $errorCorrection = ErrorCorrection::Medium,
+        int $margin = 4,
+    ): string;
+
+    /**
+     * The same SVG as a `data:image/svg+xml;base64,` URI, ready for the `src`
+     * of an `<img>` in a PDF template: the renderer never fetches anything.
+     *
+     * @param  int  $size  the edge of the square image in pixels, quiet zone included
+     * @param  int  $margin  the quiet zone around the code, in modules; 4 is what the QR standard asks for
+     *
+     * @throws InvalidArgumentException when the content is empty or too long for a QR code at that level
+     */
+    public function svgDataUri(
+        string $content,
+        int $size = 200,
+        ErrorCorrection $errorCorrection = ErrorCorrection::Medium,
+        int $margin = 4,
+    ): string;
+}
diff --git a/src/Qr/ErrorCorrection.php b/src/Qr/ErrorCorrection.php
new file mode 100644
index 0000000..e87245e
--- /dev/null
+++ b/src/Qr/ErrorCorrection.php
@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+namespace InvoiceShelf\Modules\Qr;
+
+/**
+ * How much of a QR code can be damaged and still scan, at the price of a
+ * denser code. Module API 1.6.0.
+ *
+ * Medium is right for most printed documents, and it is what the EPC
+ * (SEPA credit transfer) and Swiss QR-bill specifications require.
+ */
+enum ErrorCorrection: string
+{
+    /** About 7% of the code can be restored. */
+    case Low = 'L';
+
+    /** About 15%. */
+    case Medium = 'M';
+
+    /** About 25%. */
+    case Quartile = 'Q';
+
+    /** About 30%. */
+    case High = 'H';
+}
diff --git a/tests/QrContractsTest.php b/tests/QrContractsTest.php
new file mode 100644
index 0000000..f0ee3ec
--- /dev/null
+++ b/tests/QrContractsTest.php
@@ -0,0 +1,52 @@
+<?php
+
+declare(strict_types=1);
+
+namespace InvoiceShelf\Modules\Tests;
+
+use InvoiceShelf\Modules\Contracts\Host\QrCodeGenerator;
+use InvoiceShelf\Modules\Qr\ErrorCorrection;
+use ReflectionClass;
+use ReflectionMethod;
+
+class QrContractsTest extends TestCase
+{
+    public function test_the_host_contract_draws_svg_and_svg_data_uris_only(): void
+    {
+        $methods = array_map(
+            static fn (ReflectionMethod $method): string => $method->getName(),
+            (new ReflectionClass(QrCodeGenerator::class))->getMethods(),
+        );
+        sort($methods);
+
+        $this->assertSame(['svg', 'svgDataUri'], $methods);
+
+        foreach ($methods as $name) {
+            $method = new ReflectionMethod(QrCodeGenerator::class, $name);
+
+            $this->assertSame('string', (string) $method->getReturnType());
+            $this->assertSame(
+                ['content' => 'string', 'size' => 'int', 'errorCorrection' => ErrorCorrection::class, 'margin' => 'int'],
+                array_combine(
+                    array_map(static fn ($parameter): string => $parameter->getName(), $method->getParameters()),
+                    array_map(static fn ($parameter): string => (string) $parameter->getType(), $method->getParameters()),
+                ),
+            );
+            $this->assertSame([200, ErrorCorrection::Medium, 4], array_map(
+                static fn ($parameter) => $parameter->getDefaultValue(),
+                array_slice($method->getParameters(), 1),
+            ));
+        }
+    }
+
+    public function test_error_correction_levels_carry_the_standard_letters(): void
+    {
+        $this->assertSame(
+            ['Low' => 'L', 'Medium' => 'M', 'Quartile' => 'Q', 'High' => 'H'],
+            array_combine(
+                array_map(static fn (ErrorCorrection $level): string => $level->name, ErrorCorrection::cases()),
+                array_map(static fn (ErrorCorrection $level): string => $level->value, ErrorCorrection::cases()),
+            ),
+        );
+    }
+}