There are several solutions to read-write NTFS external hard drive and flash drive on Mac computer.
1. M3 NTFS for Mac
M3 NTFS for Mac is a NTFS driver which enables you to read and write NTFS external hard drive and flash drive on Mac OSX. M3 NTFS for Mac provides easy-to-use and intuitive UI to make NTFS read-write operations very simple. After mounting NTFS drive with M3 NTFS for Mac, M3 NTFS for Mac allows you to read and write NTFS drive as same high speed as native HFS+ drive on Mac OSX 10.11/10.10/10.9/10.8/10.7/10.6.
2. NTFS Mounter
NTFS Mounter is a snow leopard application to mount ntfs volumes in read/write mode. A simple utility designed to mount NTFS volumes in read/write mode. Although not officially supported, Snow Leopard is now able to mount NTFS volumes with both read and write support. NTFS Mounter simply uses this ability, and provides a simple user interface to the mount command for NTFS volumes. User interface is very similar to AirPort: simply click on the icon to display a menu with NTFS volumes name and select the volume you want to write on.
3. NTFS-3G for Mac OSX
NTFS-3G for Mac OS X brings NTFS read/write support to Mac OS X, along with additional advanced features. It is based on NTFS-3G, an open source NTFS driver that is ported into numerous platforms, but also includes other software projects to build a complete toolset for managing NTFS volumes. NTFS-3G for Mac requires Macfuse.
4. Mounty for NTFS
A tiny tool to re-mount write-protected NTFS volumes under Mac OS X 10.9+ in read-write mode. No additional driver will be installed. It simply makes use of the build-in mechanisms already provided by Mac OSX Mavericks
FUSE for OS X allows you to extend OS X's native file handling capabilities via third-party file systems. OSXFUSE is a successor to Small MacFUSE, which has been used as a software building block by dozens of products, but is no longer being maintained.
6. Paragon NTFS for Mac
Paragon NTFS for Mac is a driver which gives you full read and write access to Windows partitions under Mac OS X. When working with media files or documents in Mac, you need access to the high performance of your system regardless if the files are located on the Mac's HFS+ formatted volume, or in Window's NT File System. Paragon NTFS for Mac provides full read/write access to NTFS with the same high speed as native HFS+ file system
7. Tuxera NTFS for Mac
Tuxera NTFS for Mac builds and extends upon the proven stability of the open source NTFS-3G to deliver a full featured, commercial grade NTFS driver for your Mac. With Tuxera NTFS for Mac you can access your Windows disks as easily as any Mac disk. Tuxera NTFS for Mac delivers the fastest NTFS data transfer speeds you can have on Mac while protecting your data with its new, smart caching layer. The software fully supports all versions of Mac OS X from 10.4 (Tiger) onwards, including the new 64-bit kernel introduced with Snow Leopard and the upcoming Mac OS X 10.7 (Lion) and comes with advanced features only available from Tuxera such as support for NTFS extended attributes. Tuxera NTFS for Mac is compatible with popular virtualization and encryption solutions including Parallels Desktop, VMware Fusion and TrueCrypt.