Comparison

Spool Tracker vs STL Viewer

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Spool Tracker

Features
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Know exactly how much filament you have — and what every print costs. Add your whole shelf in minutes, then stop guessing for good. SpoolVault is a filament inventory built for 3D printing. Weigh a spool, log a print, and you always know what's left, what it cost, and which printer or shelf it's sitting on. ADD YOUR WHOLE SHELF IN MINUTES Pick a brand and a material, tap every color you own, set how many of each, and save them all in one go. Then do the same for your next brand. Brands, materials and colors come preloaded for Bambu Lab, eSUN, Polymaker, Prusament, Hatchbox, Overture, Inland, Sunlu, Elegoo and BIQU. KNOW WHAT'S LEFT ON EVERY SPOOL Put a spool on any kitchen scale and enter the number. SpoolVault subtracts the empty spool's weight and tells you the filament remaining. Brand-specific spool weights are already built in, so it's a real figure, not a guess. KNOW WHAT EVERY PRINT COSTS Enter what you paid for a spool and SpoolVault works out the material cost of every print from the grams used — so you finally know what the thing you just made actually cost. KNOW WHERE EVERY SPOOL IS Assign spools to a printer, an AMS or multi-material slot, and a storage location — drybox, shelf, cupboard, wherever they really live. Then find any color in seconds. GROUP A BUILD INTO A PROJECT Multi-plate print? Group the plates under one named project and see total filament used, estimated material cost, and a full breakdown of every spool that went into it. Also in the app: • Opened and unopened spools, tracked separately • Full weight history for every spool, so you can watch it come down • Search, sort and filter your whole collection • Custom brands, colors and spool weights • Saved spool-weight defaults for the spools you reuse • Export a backup of your inventory any time • No account, no sign-in — your inventory lives on your device • Works offline, in the workshop, with no signal • No ads • Free for 30 days — no subscription starts, nothing to cancel Know what's on the shelf. Know what it cost. Get back to printing. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://www.spoolvault.com/privacy-policy.html

About

STL Viewer

Features
Read full description

View STL 3D models and prepare them for 3D printing on your iPhone or iPad. Built for makers, engineers, designers, and 3D printing enthusiasts who need to open, inspect, measure, and export 3D mesh files with precision. KEY FEATURES UNIVERSAL STL SUPPORT • STL (binary and ASCII) • High-poly mesh handling • Fast file opening from Files app, share sheet, or AirDrop • Direct import from Thingiverse, Printables, MakerWorld, and other 3D model sites PRECISION MEASUREMENT TOOLS • Distance measurement between any two points on the mesh • Angle measurement across three vertices • Bounding box with exact X, Y, Z dimensions • Measurement units: mm, cm, inches PROFESSIONAL 3D INSPECTION • Solid and wireframe render modes • Smooth orbit camera with pinch-to-zoom, pan, and rotate gestures • Floor grid overlay for scale reference • Customizable model color • Real-time lit shading with directional and ambient lighting EXPORT & SHARE • Export to OBJ, DAE, and DXF formats • Capture high-resolution screenshots of any view • Share directly to Prusa Slicer, Bambu Studio, Creality Print, and other slicers • Preserve mesh integrity across exports PERFECT FOR • 3D printer owners checking models before slicing • Engineers inspecting CAD exports as STL • Designers reviewing client meshes on the go • Makers browsing Thingiverse, Printables, MakerWorld files • Students learning 3D modeling and printing • Anyone who needs to view STL files without a desktop PRECISION VIEWER • Hardware-accelerated 3D rendering • Infinite pinch-to-zoom for detailed inspection • Smooth gesture controls for any model size • Handles models with hundreds of thousands of triangles PRIVACY FIRST • All processing happens entirely on-device • No internet connection required • Your files never leave your device • Works completely offline — 100% private and secure Download now and inspect your STL files with professional-grade precision. Privacy Policy: https://nagy-legal.vercel.app/stl-viewer/privacy.html

Screenshots

Spool Tracker4 screens
STL Viewer4 screens

Verdict

The call

Spool Tracker and STL Viewer are too close to call on the numbers: across 6 compared parameters — price, update cadence, ads and in-app purchases among them — neither pulls far enough ahead to decide it. What separates them is feature set and interface, not measurable difference.

Scored on Price Ā· Rating Ā· Positive reviews Ā· Number of ratings Ā· Update frequency Ā· Ads Ā· In-app purchases Ā· Monetization Ā· Best chart rank Ā· Devices Ā· Requires iOS

CostPrice Ā· In-app purchases Ā· Ads Ā· Monetization

Both are free to download. Spool Tracker sells 2 in-app purchases, starting at $4.99 per month and STL Viewer sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

Spool Tracker ships an update fortnightly, STL Viewer every 8 days. The most recent releases landed on October 1, 2026 and October 25, 2026 respectively.

ScorecardNo meaningful differences
Spool Tracker versus STL Viewer: the parameters behind the verdict, then further details
ParameterSpool TrackerSTL Viewer
PriceFreeFree
Update frequencyFortnightlyEvery 8 days — better
AdsNoNo
In-app purchasesYesYes
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.0 — better15.1
Further details — not scored
Size36 MB39 MB
Age rating4+12+
DeveloperThree19 Pty LtdMohamed Nagy

In-app purchases

2 purchases

Spool Tracker

Subscriptions2
  • SpoolVault Premium$4.991 Month
  • SpoolVault Premium$49.991 Year
1 purchases

STL Viewer

One-time1
  • Lifetime$12.99

Questions

Is Spool Tracker free?
Spool Tracker is free to download, with in-app purchases available.
Is STL Viewer free?
STL Viewer is free to download, with in-app purchases available.
Do Spool Tracker or STL Viewer have ads?
Neither Spool Tracker nor STL Viewer shows ads.
Which is updated more often, Spool Tracker or STL Viewer?
Spool Tracker ships an update fortnightly, and STL Viewer every 8 days. Most recently, Spool Tracker was updated on October 1, 2026 and STL Viewer on October 25, 2026.

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