Some solves work best as unarmed combat. No trips to the bookshelf, no phone-a-digital-friend: just a pencil and a sore head.

Other times, though, there is little glory in leaving cells white in the grid – when the greyer cells of the brain are not up to the last couple of clues, when the puzzle is one of those barred weekend jobbies, perhaps, and especially when you're a beginner.

There are, of course, apps for that. This seems only fair: since the smartphone is probably the greatest rival to the puzzle for a solver's attention when travelling or lunching, it's only proper that the smartphone should do its bit to make sure the crossword lives on for another century.

I met the creator of one such app last year, in the course of writing Two Girls, One on Each Knee. I was keen that the index be as playful and ludic as the rest of the book and was thrilled to realise that there existed, in Denise Sutherland, a professional indexer who has also written Solving Cryptic Crosswords for Dummies, who was New South Wales's "captive cruciverbalist" on the ABC radio show Statewide Afternoon and who writes the Nixie cryptics for the Clue Detective Puzzle Agency and the Puzzle Wizard.

Denise and her husband, Dr Ralph Sutherland, created CrypticGuide for Apple devices (not Android, for those who enjoy becoming animated about such things). I've long wondered how solving tools come together, so asked Denise if she would share some thoughts.

I have been known to pack large reference works into small bags for the purpose of solving on the move; Denise's aim was to create a portable version of those tomes, including cryptic definitions, abbreviations, indicators and homophones and the meat-and-potatoes of anagram creation and wildcard search. But where do the words come from?

Your anagram solver must, I suppose, have a bank of words to check against. When you were deciding what to use as the app's lexicon, were you faced with big fees for useful lists from the rights-holders for dictionaries? And are there decent open-source word lists out there?

Yes, there are some open-source word lists. Generally, simple raw word lists, such as those used for Scrabble, are freely available. The cost issue arises once you get into the world of dictionaries and definitions. Some are marketed at up to 50 cents per definition, so a full dictionary would have been astronomically expensive for a small operation like ours.

But I've been curating word lists for my own use as a puzzle writer over decades, from a 1970s Unix spelling checklist through many electronic lists that people and organisations have freely shared online. And my husband has written programs to sort and "uniquify" (his word!) texts such as Shakespeare's works.

However, collecting long lists of raw words is not enough – they must be checked closely. A lot of word lists contain errors and computer-generated nonsense. So there's no option but to merge and edit the lists by hand.

The cryptic word database used in CrypticGuide includes associated meanings with the words and word fragments – cryptic indicators, abbreviations and so on. I could only bring these together using traditional lexicography. I slowly read a wide range of printed and electronic sources, then typed in and collected my own cryptic dictionary. It currently has nearly 7,000 headword entries. So any errors are all mine, I'm afraid!

This is, of course, a never-ending task, and I am always grateful to receive suggestions for additions to the cryptic database: abbreviations, indicators and so on. (Incidentally, we use only the simple headwords, on the basis that if "shift" is an anagram indicator, so too is "shifty".) Cryptic setters are still coming up with new ways to torment solvers, so I suspect it's a task that will never be complete.

Rewarding, though. I tend to assume that it's better to have an exhaustive word list – that most users would rather trudge through obsolete Scottish and Spenserian possibilities than miss the occasional answer. Are there technical downsides to an app having a Brobdingnagian vocabulary?

More thorough lists are always better. There aren't downsides for having these large word lists in the app, as they're pretty small in terms of bytes, and the database code can select thousands of entries quickly.

There are some interface design issues about presenting results to users, and making sure they are easy to read. We use colour-coding as one way of breaking down the information.

Abbreviations are also plentiful. How did you choose which of those to use?

I've tried to put as many in as I can find. I've put in archaic, obscure and "old-school" abbreviations, and more modern ones, from the Ximenean and the non-Ximenean camps. And naturally we've included the usual lists of chemical symbols, Roman numerals, country codes, scientific units and so on.

I've included "21st-century" abbreviations such as "lol" and "gif", because cryptic writing is constantly evolving. I also put in a lot of short foreign words, and state and region abbreviations from all those countries where cryptics are popular, including Australia, India and South Africa.

One thing I think is different from other cryptic dictionaries is that I've provided definitions. These are there for the more obscure devices that can lurk in cryptics (it took me ages to figure out why "French art" = ES!), and for more familiar abbreviations that may trip up newbie solvers.

So I hope our app helps people to learn why certain abbreviations are used, which will help them to remember them. Helping new cryptic solvers is an important goal for me: all of us were beginners once, and needed a helping hand.

I spoke to Anne R Bradford, the woman behind Bradford's Crossword Solver's Dictionary in 2011. Her book is based on observation. Have you likewise had to punctuate your solving with note-taking?

Yes, I'm always writing little notes to myself of a new abbreviation or indicator word when I'm solving, so I can add them to the database. It's very much an ongoing process.

My goal is to update the app at least once a year, to add in new terms. We certainly welcome suggestions from users via the app's feedback section if there's a term they've discovered which isn't in there.

And where did you draw the line in terms of rudeness? The first thing I typed in was "topless", and got BALD as a synonym, along with a suggestion that, unsurprisingly, I remove the first letter and more saucily, that I remove the letters BRA.

Apps have to adhere to Apple's "language standards". So there were some words that we had to expurgate from the word lists, to get a "general" rating for the app — which I objected to, but we didn't have a lot of choice in the matter.

But in terms of risque meanings, I'm all for them, and have included them whenever possible. For Solving Cryptic Crosswords for Dummies, the prudish American editors told me I had to edit out the handful of naughty clues, which I am still rather peeved about. I think cryptic crosswords do often tend towards the risque, and I don't have any problem with that.

Hear, hear. Has the experience of creating a crossword app changed the way that you solve?

I sometimes use it to look up a few words when solving a few clues now and then, especially on British cryptics (which use very different abbreviations from Australian cryptics).

My knowledge of abbreviations and indicator words is certainly better than it was – I just wish I could remember all of them perfectly. But I actually use the app most often when I'm writing cryptics.

Ah, I hadn't thought of that. It's known as DOGFOODING in the industry, I understand. Many thanks to Denise, and good luck with the Sisyphean curation and creation.