diff --git a/bin/swagger-jsdoc.js b/bin/swagger-jsdoc.js
index 339b125a..9a44a425 100755
--- a/bin/swagger-jsdoc.js
+++ b/bin/swagger-jsdoc.js
@@ -1,6 +1,7 @@
 #!/usr/bin/env node
 
 const fs = require('fs');
+const path = require('path');
 const program = require('commander');
 
 const pkg = require('../package.json');
@@ -76,6 +77,7 @@ fs.writeFileSync(
     swaggerJsdoc({
       swaggerDefinition,
       apis: program.args,
+      format: path.extname(output || ''),
     }),
     null,
     2
diff --git a/src/lib.js b/src/lib.js
index ee428862..8098870f 100644
--- a/src/lib.js
+++ b/src/lib.js
@@ -4,6 +4,7 @@ const { build } = require('./specification');
  * Generates the specification.
  * @param {object} options - Configuration options
  * @param {string} options.encoding Optional, passed to readFileSync options. Defaults to 'utf8'.
+ * @param {string} options.format Optional, defaults to '.json' - target file format '.yml' or '.yaml'.
  * @param {object} options.swaggerDefinition
  * @param {object} options.definition
  * @param {array} options.apis
diff --git a/src/specification.js b/src/specification.js
index f58d3821..eb8f4648 100644
--- a/src/specification.js
+++ b/src/specification.js
@@ -55,6 +55,17 @@ function prepare(definition) {
   return swaggerObject;
 }
 
+/**
+ * @param {object} obj
+ * @param {string} ext
+ */
+function format(swaggerObject, ext) {
+  if (ext === '.yml' || ext === '.yaml') {
+    return YAML.stringify(swaggerObject);
+  }
+  return swaggerObject;
+}
+
 /**
  * OpenAPI specification validator does not accept empty values for a few properties.
  * Solves validator error: "Schema error should NOT have additional properties"
@@ -82,7 +93,7 @@ function clean(swaggerObject) {
  * @param {object} swaggerObject - Swagger object from parsing the api files.
  * @returns {object} The specification.
  */
-function finalize(swaggerObject) {
+function finalize(swaggerObject, options) {
   let specification = swaggerObject;
 
   parser.parse(swaggerObject, (err, api) => {
@@ -95,7 +106,7 @@ function finalize(swaggerObject) {
     specification = clean(specification);
   }
 
-  return specification;
+  return format(specification, options.format);
 }
 
 /**
@@ -265,7 +276,7 @@ function build(options) {
     }
   }
 
-  return finalize(specification);
+  return finalize(specification, options);
 }
 
-module.exports = { prepare, build, organize, finalize };
+module.exports = { prepare, build, organize, finalize, format };
diff --git a/test/specification.spec.js b/test/specification.spec.js
index 25ad64fa..148881e2 100644
--- a/test/specification.spec.js
+++ b/test/specification.spec.js
@@ -95,4 +95,15 @@ describe('Specification module', () => {
       });
     });
   });
+
+  describe('format', () => {
+    it('should not modify input object when no format specified', () => {
+      expect(specModule.format({ foo: 'bar' })).toEqual({ foo: 'bar' });
+    });
+
+    it('should support yaml', () => {
+      expect(specModule.format({ foo: 'bar' }, '.yaml')).toEqual('foo: bar\n');
+      expect(specModule.format({ foo: 'bar' }, '.yml')).toEqual('foo: bar\n');
+    });
+  });
 });