Your stash is full again and you have no idea what half this stuff does. Here are the rules. Follow them and you'll stop accidentally selling things you need and stop hoarding junk you don't.

The cheat sheet
1. Trinkets? Always sell. They exist for exactly one reason: credits.
2. Quest items? Always keep until the quest is done. Check trader requirements before you dump anything.
3. Workshop materials (Motors, Cooling Coils, Industrial Batteries, Lab Reagents, Rusted Gears)? Keep. Every single one.
4. ARC boss components (Matriarch Reactor 13,000c, Queen Reactor 11,000c, Ion Sputter 6,000c)? Sell unless you need them for a specific craft.
5. Broken/damaged items (Damaged Heat Sinks, Alarm Clocks, Spectrometers, Microscopes)? Recycle for components.
6. Fruits and mushrooms? Recycle into Assorted Seeds.
For item-by-item lookups, use the loot cheat sheet.
The golden rule
If you don't know what an item does, look it up before selling it. That's it. Five seconds of checking can save you hours of farming. The number of players who've sold a stack of Motors only to discover they need them for a Tier 3 workbench upgrade is genuinely painful. Use the loot cheat sheet or search the item in the full item database to see every use for it.

Keep
Motor

Keep
Ind. Battery

Sell
Boss drops
Items that look like junk but aren't

KEEP
Motor

KEEP
Ind. Battery
This is where new players get burned the most. These items have boring names and no obvious purpose, so people sell them for a few hundred credits and move on. Big mistake.
Do NOT sell these.
Motors are required for multiple workbench upgrades and late-game crafting recipes. They're rare. Every Motor you sell is one you'll have to farm again later.
Cooling Coils show up in weapon workbench upgrades. The drop rate is low enough that you'll notice when you don't have them.
Rusted Gears look like actual trash. They're not. They're needed for several mid-tier workshop projects.
Industrial Batteries are used in equipment crafting and workbench progression. Keep all of them.
Lab Reagents are needed for medical supply upgrades. You won't need many early on, but when you do need them, you'll wish you hadn't sold them.
The pattern here is simple: workshop materials are always rare and always needed. If an item's description mentions "workshop" or "crafting" in any way, keep it.
High-value sells

Boss weapons

Valuable gear

Meta weapons
These are the items you actually want to sell. They come from ARC bosses and tough encounters, and they're worth serious credits.
These are all boss drops. The Matriarch Reactor alone pays for a full loadout. Unless you're actively working on a craft that needs one of these components, sell them. You can always farm the boss again, and the credits are too good to pass up.
Look up any item instantly in the Raidex app
Search by name, see the sell price, recycle output, crafting uses, and our keep/sell/recycle recommendation. Works offline during raids.
When to recycle vs sell
This confuses a lot of people, but there's a pretty clean line. Items worth more than 2,000c in sell value are almost always better to sell outright. The credits are more useful than whatever components you'd get from the recycler. Items under 1,000c that return electrical or mechanical components are better to recycle, because those components are used in crafting recipes that would cost you more than 1,000c to source otherwise.
The gray zone is between 1,000c and 2,000c. For those items, check what components they return. If you need those components for something you're actively crafting, recycle. If not, sell.
Better to sell
Boss components (5,000c+), high-value ARC parts, trinkets, and anything above 2,000c that you don't need for crafting.
Better to recycle
Damaged Heat Sinks, Alarm Clocks, Spectrometers, Microscopes, fruits, mushrooms, and low-value junk that returns electrical or mechanical components.
What Flashpoint changed

The Flashpoint update overhauled the crafting UI, and it's a huge quality-of-life win for item management. You can now see exactly what materials a recipe needs from a single window. No more tabbing between menus trying to remember if you need two Cooling Coils or three.
The new Scrappy Feeding Boost system also matters here. Recycling certain items now contributes to a boost meter that increases the output of future recycling runs. So if you're going to recycle a batch of items, do them all at once to stack the boost.
Two new boss drops were added with the Vaporizer and ARC Assessor enemies. Vaporizer Regulators (6,000c) and Assessor Matrices (5,000c) follow the same rule as other boss drops: sell them unless you have a specific craft waiting.
Expedition items and stash value
Expeditions add another layer to the keep-or-sell decision. Certain items are needed for expedition projects, and those are always worth keeping until the project is complete. Check your active expedition requirements before cleaning out your stash.
There's also the stash value mechanic. Your total stash value matters for expedition progression, with the big milestone sitting at 5M credits in stash value. This means sometimes it's worth holding onto high-value items instead of selling them, at least until you've hit that threshold. A Matriarch Reactor sitting in your stash contributes 13,000c to your stash value without you spending anything. Once you've passed the milestone, go ahead and sell.
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Frequently Asked Questions
What items should I never sell in ARC Raiders?
Workshop materials: Motors, Cooling Coils, Industrial Batteries, Lab Reagents, and Rusted Gears. These are rare, they're needed for workbench upgrades and high-tier crafting, and you will regret selling them. Also keep any quest items until you've finished the associated quest line. Use the loot cheat sheet to check any item you're not sure about.
Should I recycle or sell items in ARC Raiders?
Sell anything worth over 2,000c. Recycle anything under 1,000c that gives back useful components (electrical, mechanical). For items in the 1,000-2,000c range, check if you need the components for something you're actively crafting. Broken and damaged items like Damaged Heat Sinks and Alarm Clocks should almost always go in the recycler.
What are trinkets for in ARC Raiders?
Trinkets exist to be sold. That's literally their only purpose. They have no crafting use, no quest requirement, and recycling them returns almost nothing. Sell every trinket the moment you extract with it.