Because IndexedDB is a W3C spec[0] intended for web browsers and LevelDB is a third-party npm module[1].<p>Node is just a JS environment. Implementing IndexedDB is as much out of scope as implementing XHR[2] or the File API[3]. In fact it provides the building blocks developers to implement any of these on top of Node should they need to (like node-fetch[4] implementing the Fetch API[5] for isomorphic apps).<p>[0]: <a href="http:&#x2F;&#x2F;www.w3.org&#x2F;TR&#x2F;IndexedDB&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.w3.org&#x2F;TR&#x2F;IndexedDB&#x2F;</a><p>[1]: <a href="http:&#x2F;&#x2F;leveldb.org&#x2F;" rel="nofollow">http:&#x2F;&#x2F;leveldb.org&#x2F;</a><p>[2]: <a href="https:&#x2F;&#x2F;xhr.spec.whatwg.org&#x2F;" rel="nofollow">https:&#x2F;&#x2F;xhr.spec.whatwg.org&#x2F;</a><p>[3]: <a href="http:&#x2F;&#x2F;www.w3.org&#x2F;TR&#x2F;FileAPI&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.w3.org&#x2F;TR&#x2F;FileAPI&#x2F;</a><p>[4]: <a href="https:&#x2F;&#x2F;www.npmjs.com&#x2F;package&#x2F;node-fetch" rel="nofollow">https:&#x2F;&#x2F;www.npmjs.com&#x2F;package&#x2F;node-fetch</a><p>[5]: <a href="https:&#x2F;&#x2F;fetch.spec.whatwg.org&#x2F;" rel="nofollow">https:&#x2F;&#x2F;fetch.spec.whatwg.org&#x2F;</a>