Add serialif color api

README.md

@@ -312,6 +312,7 @@ API | Description | Auth | HTTPS | CORS |
 | [scrapestack](https://scrapestack.com/) | Real-time, Scalable Proxy & Web Scraping REST API | `apiKey` | Yes | Unknown |
 | [ScrapingDog](https://www.scrapingdog.com/) | Proxy API for Web scraping | `apiKey` | Yes | Unknown |
 | [ScreenshotAPI.net](https://screenshotapi.net/) | Create pixel-perfect website screenshots | `apiKey` | Yes | Yes |
+| [Serialif Color](https://color.serialif.com/) | Color conversion, complementary, grayscale and contrasted text | No | Yes | No |
 | [serpstack](https://serpstack.com/) | Real-Time & Accurate Google Search Results API | `apiKey` | Yes | Yes |
 | [SHOUTCLOUD](http://shoutcloud.io/) | ALL-CAPS AS A SERVICE | No | No | Unknown |
 | [StackExchange](https://api.stackexchange.com/) | Q&A forum for developers | `OAuth` | Yes | Unknown |