FTS to AZW3 Converter

Produce AZW3 from FTS — browser-based converter

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Secure Processing

Your FTS uploads are deleted right after conversion, and the resulting AZW3 output is removed from servers within 24 hours for full privacy.

Cross-Platform

The converter works on Windows, macOS, Linux, iOS, and Android. Convert FTS to AZW3 from whichever device you have at hand.

No Install Needed

The converter runs entirely in your browser — no desktop software required. Works on all major platforms and devices alike.

How to convert FTS to AZW3

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose azw3 or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your azw3 file right afterwards

About formats

FTS is a file extension for the Flexible Image Transport System (FITS), the standard data format used in astronomy since 1981 when it was defined by Don Wells, Eric Greisen, and R.H. Harten at the National Radio Astronomy Observatory, and subsequently endorsed by the International Astronomical Union in 1982. FITS was designed from the outset as a self-describing archival format: each file begins with one or more 2880-byte header blocks containing ASCII keyword-value pairs that describe the data's dimensions, coordinate system, observation parameters, and provenance, followed by data blocks in a variety of numeric types — 8/16/32/64-bit integers and 32/64-bit IEEE floating-point values. FITS supports multi-dimensional arrays (images, data cubes, hypercubes), binary tables for catalog data, and ASCII tables, with multiple Header/Data Units (HDUs) that can coexist in a single file. The format handles specialized astronomical data: spectral cubes, radio interferometry visibilities, multi-extension mosaic images from CCD arrays, and time-series photometry. One advantage is scientific rigor: FITS mandates that all metadata needed to interpret the data physically — coordinate transformations (WCS), photometric calibration, telescope and instrument parameters — travels with the file, eliminating the metadata-loss problem that plagues general-purpose image formats in scientific contexts. The format's longevity and institutional backing is another strength — virtually every observatory, space telescope (Hubble, James Webb, Chandra), and astronomical software package (DS9, IRAF, Astropy) uses FITS as its primary data format.
Developer: NASA / IAU
Initial release: 1981
AZW3, also known as Kindle Format 8 (KF8), is Amazon's advanced ebook format introduced in November 2011 alongside the first Kindle Fire tablet. It replaced the older MOBI-based AZW format with a substantially more capable layout engine built on HTML5 and CSS3 subsets, enabling fixed layouts, embedded fonts, SVG graphics, drop caps, and other typographic refinements that were impossible in earlier Kindle formats. Internally, an AZW3 file packages content in a structure derived from EPUB, wrapped in Amazon's proprietary Palm database container with optional DRM protection. The format supports both reflowable text for novels and fixed-layout pages for comics, cookbooks, and children's titles. One major advantage is rich formatting fidelity — publishers can produce visually sophisticated ebooks with complex page designs, nested tables, and precise font control that render consistently across the Kindle ecosystem. Another strength is backward compatibility: AZW3 files can bundle a MOBI fallback section so older Kindle hardware still displays the content, even without full KF8 rendering. The format integrates tightly with Amazon's Kindle platform, supporting features like X-Ray, Whispersync page tracking, and in-book dictionary lookups across millions of devices and apps worldwide.
Developer: Amazon
Initial release: November 2011

Frequently Asked Questions

Why convert FTS to AZW3?

Amazon kindle ebook format — converting FTS to AZW3 gives your astronomical images broader reach and easier sharing across standard platforms.

What programs open AZW3?

E-reader apps and devices open AZW3 — Kindle, Calibre, Apple Books, and most e-reader hardware support this format.

Can I convert multiple FTS images at once?

Yes — upload several FTS images in one session and convert them all to AZW3 simultaneously. Batch processing saves significant time.

Does this work on mobile devices?

Yes — the converter runs in any web browser, so it works on phones, tablets, laptops, and desktops regardless of operating system.

Do I need FTS software installed?

No — the converter processes FTS entirely in the cloud. You do not need any astronomy and scientific research software on your device to convert.

How long does the conversion take?

Most FTS to AZW3 conversions finish within seconds. Larger or more complex images may take slightly longer depending on the data size.