Nalaprop – multilingual natural language parsing

Updated! Parses multilingual text to mark up its different parts of speech. Documentation include relevant source code. Works brilliantly in Dark Mode. Eighth beta release, notarized, analyses interactively while you are writing, word frequency counts include option to count by stem/root (lemma) of word, extensive find, colour keys. Now supports changing font size in all three panels.
Nalaprop 1.0b10 (Intel-only for Mojave and Catalina)
Nalaprop 1.2 (Universal App for Mojave, Catalina, Big Sur, Monterey, Ventura and Sonoma)

Dystextia – encodes and decodes Unicode Latin text using unconventional code points

A unique app which lets you explore hidden reaches of Unicode. Converts text so that it can still be read normally by a human, but uses weird character encodings which break search and string comparison operations. Can be used to electronically obfuscate text, for privacy, spoofing, and more. Version 1.8 has been refreshed for Sonoma.
Dystextia 1.6 (Intel-only for Sierra, High Sierra, Mojave and Catalina)
Dystextia 1.8 (Universal App for High Sierra, Mojave, Catalina, Big Sur, Monterey, Ventura and Sonoma)

Apfelstrudel – check the normalisation of Unicode text, to spot potential problems with file systems other than HFS+

Apfelstrudel details the four Unicode normalisation forms for entered text, including that for the Mac Extended file system, HFS+. Use it to explore potential problems with normalisation, such as working with Linux and Apple’s new APFS file systems, and to explore Unicode representations of text. This update has been refreshed for Sonoma.
Apfelstrudel 1.3 (Intel-only for Sierra, High Sierra, Mojave and Catalina)
Apfelstrudel 1.5 (Universal App for High Sierra, Mojave, Catalina, Big Sur, Monterey, Ventura and Sonoma)

Rosettavert – converts between different text encodings

Uses the command tool iconv to perform conversions between around 144 different text encodings. Greatly improved, with extensive help and better encoding selection, and fixes window resizing bug.
Rosettavert 1.4 (Intel-only for Sierra, High Sierra, Mojave and Catalina)
Rosettavert 1.5 (Universal App for Sierra, High Sierra, Mojave, Catalina, Big Sur and Monterey)

unorml – a command tool to normalise a string to any of the four Unicode forms

unorml converts the string supplied as its argument to any of the four (C, D, KC, KD) Unicode normalised forms, and helps you address normalisation issues, as may arise on Apple’s new file system, APFS. Now a Universal binary, and compatible with Sonoma.
unorml 3 (Intel-only for Sierra to Catalina)
unorml 4a (Universal App for Sierra to Monterey)
unorml 5 (Universal App for Big Sur, Monterey, Ventura and Sonoma)

Known Issues:

Nalaprop is unlikely to print correctly when in Dark Mode. I will fix this in a future version.

Articles:

Analysing natural languages with Nalaprop
unorml, a command tool to normalise strings, now a Universal binary
Rosettavert version 1.5 is now available as a Universal App
Fun and confuddling with Unicode
Dystextia version 1.7 is now a Universal App
Apfelstrudel version 1.4 is now a Universal App
Ending Mojibake with Rosettavert 1.3
28 years after Unicode, we still can’t handle accents: PDF + macOS + URL = chaos