AZW3 to FTS Converter

Convert AZW3 to FTS online — free FITS images

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Scientific Image Output

Transform AZW3 ebook pages into FTS images — the FITS standard used by astronomers and researchers for scientific data.

Speedy Processing

High-performance cloud servers render your FTS output in seconds, delivering results without any wait or local strain.

Secure Conversion

Your AZW3 upload is deleted immediately after conversion and FTS results are cleaned from servers within 24 hours.

How to convert AZW3 to FTS

1

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

2

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

3

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

About formats

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
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

Frequently Asked Questions

Why convert AZW3 to FTS?

FTS (FITS) is the scientific imaging standard. Converting creates FTS images from ebook pages for use in research or data analysis tools.

What opens FTS files?

SAOImageDS9, FITS Liberator, Aladin, GIMP (with plugin), and astronomical data analysis software like IRAF support FTS images.

Is FTS a common image format?

Not for general use — FTS is primarily found in astronomy and scientific imaging. It stores metadata alongside pixel data for analysis.

How fast is AZW3 to FTS conversion?

Seconds for most ebooks. All rendering takes place on cloud infrastructure so your machine is not burdened at all.

Is the conversion free?

Completely free. Convertio converts AZW3 to FTS at no charge. Premium options add batch capabilities and larger uploads.