I need a little advice from anyone with some experience at canning.

I've got a whole whack of crabapples at work, and would like to make crabapple jelly. I'm OK with that part - I've made it before and feel comfortable with it. However, I haven't got any jars, and would really rather avoid the jars in boiling water part.

Is it possible to freeze my jelly in some other containers, as if it were freezer jam? I wouldn't be using pectin, as there is already so much in apples, but all the freezer jam recipes I've seen call for added pectin, even for apple jams. Has anyone ever frozen jelly? How did it turn out? Am I running any risks of contamination, if I don't process jars?

Umm ... I've never sterilised or processed jars when I make jam or jelly, and everything keeps just fine! I do pour the jam or jelly piping hot into the jars and screw on the lids immediately. I turn them upsidedown for 5-10 minutes to assure a seal, then leave them to cool right side up. This year I finished off our jams from 2009, not a hint of anything unsavoury growing on them, and the taste was fine.

I also do not use added pectin, though I do regularly squeeze half a lemon into the fruit mixture, so that might count?

We sterilize our jars in the dishwasher by running them without soap. We don't water bath can our jelly, we pour it into sterilized jars and once it cools a bit, top it with paraffin. I've never done freezer jam.

Agony - I agree pretty much with the last two Kitchen Goddesses
Jam/jelly recipes from Australia's acknowledged Gurus (Country Women's Association et al) are never processed in a water bath.
I recycle used glass jars from store-bought pickles, mayo, olives etc. provided they have an acid-resistant lid. I remove labels and glue and wash jars and lids on hottest cycle of dishwasher. Store empty jars, lids on, until ready for use.
No need for special jars, seals, clips.
While jam or jelly is reaching setting point, take lids off jars and heat both in an oven about 100degC. for just a few minutes.
Pour hot jam into hot jars and seal immediately. Turn upside -down for a few minutes if you wish. I am confident this will keep in a dark cupboard for a minimum of one year.
I always add strained lemon juice, at least 1 lemon per kg of fruit, so very rarely need pectin to obtain a set.
I had never heard of freezer jam until your post!

Very helpful, thanks, all of you.

How can I tell if the lid is acid resistant? I suppose it would have to be, for pickles, eh?

Pretty much. If the lid is scratched or slightly discoloured inside, don't use it.
If you don't have enough lids for your jars, Rayven's idea of paraffin wax seals will work.

I've never re-used jars from store-bought pickles etc. I don't believe they were ever meant to be used more than once and so don't trust them to keep a good seal. (I do recycle certain shapes as spice jars though, as they will hold a whole bag or two).

My grandmother gave me all her mason jars (LOADS of them - so many they have to be stored in the garage lol), but I tend to use the small ones the most (and if people don't return my jars, they don't get any more preserves from me lol). With smaller jars, there is no issue with spoilage as the contents are normally used up within three weeks at most.

You DO have to buy new lid liners and/or rubber rings as the first rust over time and the latter wear out/become hard. I always top the jelly/jam with paraffin wax in addition to putting the usual ring/lid on the jar. I put the jars in the dishwasher on hot, after which I pour BOILING water in them to rinse before filling.

Pioneer and "Depression era" children from countries with hard winters were fond of simmering in a "bath" or pressure cooker style, because things could keep up to two (or more) years that way, so it was practical and sensible when you didn't know when your next good crop might come around (and of course, didn't have the luxury of refrigerators). But you lose quality/fresh-taste/nutrient value with that method. The contents continue to cook in the bath, so they are less crisp (talking about pickles here, carrots, beets, beans etc) and they don't keep their colour either. With veggies (excluding cucumbers) I blanch them to the desired degree of crisp/tenderness and then plunge them in ice water. Yes, the brine that is poured over them eventually is HOT, but at least the veggies haven't been slow cooking in all that time lol.

I don't see any real advantage with "freezer" type jam. You still need to cook the fruit and put it in a clean container, so there's no saving on "work" as far as I can see. Besides, my freezer space is limited, but I have plenty of cupboards : )

By the way, lemon juice contains pretty much NO pectin whatsoever. However, its acidity reacts with sugar and somewhat helps with jelling liquids. No amount of lemon juice will help with fruits like blueberries, sour cherries or peaches for instance as the amount of sugar/lemon juice you'd have to put in would be a ridiculous (and unhealthy) amount. Jellies and jams are two different things entirely of course : )