These are last known good working URLs on adobe.com to .zip downloads of the Adobe Flex SDK from version 2.0 Hotfix 1, and 3.0.0 to 4.6.0.
Note: As of June 2024, these URLs were still active, but it is best to assume that they could be removed by Adobe at any time, without notice. If you anticipate needing any of these versions of the Adobe Flex SDK in the future, you should download and keep a backup copy somewhere safe. If these URLs are removed, you may be able to use the Apache Flex SDK instead. To download the Apache Flex SDK, visit https://flex.apache.org/download-binaries.html
- https://download.macromedia.com/pub/flex/sdk/flex2_sdk_hf1.zip
- https://fpdownload.adobe.com/pub/flex/sdk/builds/flex3/flex_sdk_3.0.0.477A.zip
- https://fpdownload.adobe.com/pub/flex/sdk/builds/flex3/flex_sdk_3.0.1.1732A.zip
- https://fpdownload.adobe.com/pub/flex/sdk/builds/flex3/flex_sdk_3.1.0.2710A.zip
- https://fpdownload.adobe.com/pub/flex/sdk/builds/flex3/flex_sdk_3.2.0.3958A.zip
- https://fpdownload.adobe.com/pub/flex/sdk/builds/flex3/flex_sdk_3.3.0.4852A.zip
- https://fpdownload.adobe.com/pub/flex/sdk/builds/flex3/flex_sdk_3.4.1.10084A.zip
- https://fpdownload.adobe.com/pub/flex/sdk/builds/flex3/flex_sdk_3.5.0.12683B.zip
- https://fpdownload.adobe.com/pub/flex/sdk/builds/flex3/flex_sdk_3.6.0.16995A.zip
- https://fpdownload.adobe.com/pub/flex/sdk/builds/flex4/flex_sdk_4.0.0.14159A.zip
- https://fpdownload.adobe.com/pub/flex/sdk/builds/flex4/flex_sdk_4.1.0.16076A.zip
- https://fpdownload.adobe.com/pub/flex/sdk/builds/flex4.5/flex_sdk_4.5.0.20967A.zip
- https://fpdownload.adobe.com/pub/flex/sdk/builds/flex4.5/flex_sdk_4.5.1.21328A.zip
- https://fpdownload.adobe.com/pub/flex/sdk/builds/flex4.6/flex_sdk_4.6.0.23201B.zip