diff --git a/CHANGELOG.md b/CHANGELOG.md
index 381021fb..e5a78e82 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com), and this
   For example, if you did not enable RabbitMQ real-time updates, instead of triggering a job that ends immediately, the job will not even be enqueued.
 
 * [#1835](https://github.com/shlinkio/shlink/issues/1835) Docker image is now built only when a release is tagged, and new tags are included, for minor and major versions.
+* [#1055](https://github.com/shlinkio/shlink/issues/1055) Update OAS definition to v3.1.
 
 ### Deprecated
 * [#1783](https://github.com/shlinkio/shlink/issues/1783) Deprecated support for openswoole. RoadRunner is the best replacement, with the same capabilities, but much easier and convenient to install and manage.
diff --git a/composer.json b/composer.json
index ba72eed1..d9e0e63f 100644
--- a/composer.json
+++ b/composer.json
@@ -63,7 +63,7 @@
         "symfony/string": "^6.2"
     },
     "require-dev": {
-        "cebe/php-openapi": "^1.7",
+        "devizzent/cebe-php-openapi": "^1.0.1",
         "devster/ubench": "^2.1",
         "infection/infection": "^0.27",
         "openswoole/ide-helper": "~22.0.0",
diff --git a/docs/swagger/definitions/DeviceLongUrls.json b/docs/swagger/definitions/DeviceLongUrls.json
index 1a56d9ef..0e8719db 100644
--- a/docs/swagger/definitions/DeviceLongUrls.json
+++ b/docs/swagger/definitions/DeviceLongUrls.json
@@ -3,18 +3,15 @@
     "properties": {
         "android": {
             "description": "The long URL to redirect to when the short URL is visited from a device running Android",
-            "type": "string",
-            "nullable": false
+            "type": ["string"]
         },
         "ios": {
             "description": "The long URL to redirect to when the short URL is visited from a device running iOS",
-            "type": "string",
-            "nullable": false
+            "type": ["string"]
         },
         "desktop": {
             "description": "The long URL to redirect to when the short URL is visited from a desktop browser",
-            "type": "string",
-            "nullable": false
+            "type": ["string"]
         }
     }
 }
diff --git a/docs/swagger/definitions/DeviceLongUrlsEdit.json b/docs/swagger/definitions/DeviceLongUrlsEdit.json
index 78f77e46..f1ff255f 100644
--- a/docs/swagger/definitions/DeviceLongUrlsEdit.json
+++ b/docs/swagger/definitions/DeviceLongUrlsEdit.json
@@ -5,13 +5,13 @@
     }],
     "properties": {
         "android": {
-            "nullable": true
+            "type": ["null"]
         },
         "ios": {
-            "nullable": true
+            "type": ["null"]
         },
         "desktop": {
-            "nullable": true
+            "type": ["null"]
         }
     }
 }
diff --git a/docs/swagger/definitions/NotFoundRedirects.json b/docs/swagger/definitions/NotFoundRedirects.json
index 6887ed0c..d0459f90 100644
--- a/docs/swagger/definitions/NotFoundRedirects.json
+++ b/docs/swagger/definitions/NotFoundRedirects.json
@@ -2,18 +2,15 @@
     "type": "object",
     "properties": {
         "baseUrlRedirect": {
-            "type": "string",
-            "nullable": true,
+            "type": ["string", "null"],
             "description": "URL to redirect to when a user hits the domain's base URL"
         },
         "regular404Redirect": {
-            "type": "string",
-            "nullable": true,
+            "type": ["string", "null"],
             "description": "URL to redirect to when a user hits a not found URL other than an invalid short URL"
         },
         "invalidShortUrlRedirect": {
-            "type": "string",
-            "nullable": true,
+            "type": ["string", "null"],
             "description": "URL to redirect to when a user hits an invalid short URL"
         }
     }
diff --git a/docs/swagger/definitions/OrphanVisit.json b/docs/swagger/definitions/OrphanVisit.json
index 04d8386d..a8b4954a 100644
--- a/docs/swagger/definitions/OrphanVisit.json
+++ b/docs/swagger/definitions/OrphanVisit.json
@@ -6,8 +6,7 @@
     }],
     "properties": {
         "visitedUrl": {
-            "type": "string",
-            "nullable": true,
+            "type": ["string", "null"],
             "description": "The originally visited URL that triggered the tracking of this visit"
         },
         "type": {
diff --git a/docs/swagger/definitions/ShortUrl.json b/docs/swagger/definitions/ShortUrl.json
index 4060e2f2..98fd9c87 100644
--- a/docs/swagger/definitions/ShortUrl.json
+++ b/docs/swagger/definitions/ShortUrl.json
@@ -55,13 +55,11 @@
             "$ref": "./ShortUrlMeta.json"
         },
         "domain": {
-            "type": "string",
-            "nullable": true,
+            "type": ["string", "null"],
             "description": "The domain in which the short URL was created. Null if it belongs to default domain."
         },
         "title": {
-            "type": "string",
-            "nullable": true,
+            "type": ["string", "null"],
             "description": "A descriptive title of the short URL."
         },
         "crawlable": {
diff --git a/docs/swagger/definitions/ShortUrlEdition.json b/docs/swagger/definitions/ShortUrlEdition.json
index ed3c3929..dda213ca 100644
--- a/docs/swagger/definitions/ShortUrlEdition.json
+++ b/docs/swagger/definitions/ShortUrlEdition.json
@@ -10,18 +10,15 @@
         },
         "validSince": {
             "description": "The date (in ISO-8601 format) from which this short code will be valid",
-            "type": "string",
-            "nullable": true
+            "type": ["string", "null"]
         },
         "validUntil": {
             "description": "The date (in ISO-8601 format) until which this short code will be valid",
-            "type": "string",
-            "nullable": true
+            "type": ["string", "null"]
         },
         "maxVisits": {
             "description": "The maximum number of allowed visits for this short code",
-            "type": "number",
-            "nullable": true
+            "type": ["number", "null"]
         },
         "validateUrl": {
             "deprecated": true,
@@ -36,9 +33,8 @@
             "description": "The list of tags to set to the short URL."
         },
         "title": {
-            "type": "string",
-            "description": "A descriptive title of the short URL.",
-            "nullable": true
+            "type": ["string", "null"],
+            "description": "A descriptive title of the short URL."
         },
         "crawlable": {
             "type": "boolean",
diff --git a/docs/swagger/definitions/ShortUrlMeta.json b/docs/swagger/definitions/ShortUrlMeta.json
index 370a548b..d687d97f 100644
--- a/docs/swagger/definitions/ShortUrlMeta.json
+++ b/docs/swagger/definitions/ShortUrlMeta.json
@@ -4,18 +4,15 @@
     "properties": {
         "validSince": {
             "description": "The date (in ISO-8601 format) from which this short code will be valid",
-            "type": "string",
-            "nullable": true
+            "type": ["string", "null"]
         },
         "validUntil": {
             "description": "The date (in ISO-8601 format) until which this short code will be valid",
-            "type": "string",
-            "nullable": true
+            "type": ["string", "null"]
         },
         "maxVisits": {
             "description": "The maximum number of allowed visits for this short code",
-            "type": "number",
-            "nullable": true
+            "type": ["number", "null"]
         }
     }
 }
diff --git a/docs/swagger/swagger.json b/docs/swagger/swagger.json
index b80ae3b2..51655ecf 100644
--- a/docs/swagger/swagger.json
+++ b/docs/swagger/swagger.json
@@ -1,5 +1,5 @@
 {
-    "openapi": "3.0.3",
+    "openapi": "3.1.0",
     "info": {
         "title": "Shlink",
         "description": "Shlink, the self-hosted URL shortener",