STEALTHMARK · HEAD TO HEAD

All comparisons ↗

Iceman Contributor vs Callstack Apex

Callstack Apex leads Iceman Contributor by 30.3 points on StealthMark, 49.5 to 19.2. It leads on all 8 benchmarks with results for both. Pixel Canary scores higher on Newton's Mirror, with its largest category advantage in state at 600 ms.

See the difference ↘
Model guide ↗
Model guide ↗

Overall StealthMark

19.2/100Overall rank 47/53
49.5/100Overall rank 18/53

General Intelligence

11.7/100
40.4/100

Visual Intelligence

31.0/100
59.6/100

Reasoning efficiency

On every task, result quality and reasoning tokens are each compared with all measured models and weighed equally. Each dot is one model.

Single-step reasoning Result quality weighed against reasoning tokens on a single problem

Multi-step reasoning Result quality weighed against reasoning tokens across connected steps, as in agentic workflows

Open or local

BENCHMARK BY BENCHMARK

Where each model leads

  • Iceman Contributor
  • Callstack Apex
  • Other models
  • Median

DATASHEET

Specs and pricing

Callstack Apex scores higher on StealthMark and runs 5.5× faster in our speed test.

  • Iceman Contributor
  • Callstack Apex
  • Other models
  • Median
PricePer 1M output tokens, input below
Iceman Contributor: No list priceCallstack Apex: $3$0.50 input
Context windowTokens per request, max output below
Iceman Contributor: Not publishedCallstack Apex: 256K
Output speedTokens per second, our measurement
Iceman Contributor: 46tokens/sCallstack Apex: 2555.5× fastertokens/s
Developer
Not publishedCallstack
Released
Not published1 Oct 2026
Origin
Not publishedPoland
Input → output
Not publishedText → text
Architecture
Not publishedQwen foundation with Callstack domain post-training for React and React Native

Full datasheets, every price and sourceCallstack Apex ↗

Anticipating threats and planning ahead. Collect coins while avoiding ghosts. Ghosts move before the player each turn, and collisions cost a life. 3 levels in sequence, up to 66 turns in total. Earlier moves and outcomes carry forward, testing learning across levels.

Iceman Contributor 3.2/100Rank 47/47

Survived 0 of 3
Foresight: complete playing field
Level 31 ptsTurn 7 / 20

Points per level

LevelIceman ContributorCallstack Apex
Level 1Second Thoughts
0 ptsOut of lives
No run
Level 2Pressure Pot
3 ptsOut of lives
No run
Level 3Hide or Flight
1 ptsOut of lives
No run

Cooperative planning and learning from experience. Coordinate two robots to push numbered cores onto matching sockets. Pressure plates hold doors open; moving either robot uses one turn. 5 levels in sequence, up to 152 turns in total. Earlier moves and outcomes carry forward, testing learning across levels.

Iceman Contributor 3.6/100Rank 44/48

Cleared 1 of 5
Latch: complete playing field
Level 55 ptsTurn 25 / 40

Callstack Apex 100.0/100Rank 40/481 of 5 levels

1 of 5 played
Latch: complete playing field
Level 15.2 ptsTurn 6 / 12

Points per level

LevelIceman ContributorCallstack Apex
Level 1Hold the door
5.2 ptsCleared
5.2 ptsCleared
Level 2Crossfeed
2.8 ptsFinished early
Pending
Level 3Relay vault
2.2 ptsFinished early
Pending
Level 4Passing bay
4 ptsFinished early
Not played
Level 5Second thoughts
5 ptsFinished early
Not played

Newton's Mirror

Same task instructions

Physics, perspective and recursive reflections, tested together. Explore the test ↗

The judgment

Iceman Contributor

The image provides limited evidence through rounded volume, faint wall strips and floor echoes. Its main sphere is small and low, the paint beads do not establish the required interaction history, and most of the defining mirror structure is missing.

Callstack Apex

The principal sphere placement and paint contact sequence are supported. Isolated sphere and panel images provide limited optical structure, but missing lateral chains and side-floor continuations prevent a coherent repeating mirror room. The main and reflected spheres lack ordered curved nested imagery, while sparse planar emitter images and incomplete spherical emitter mapping leave most of the reflection system unsupported.

Score breakdown

CategoryIceman ContributorCallstack Apex
State at 600 ms0.5/2520.0/25
Camera and placement2.5/1513.0/15
Reflections7.5/12010.0/120
Materials and scale3.0/107.0/10
Floor-damage reward0.0/100.0/10

Benchmark task

A spinning metal sphere and paint in a mirrored room test physical reasoning, perspective and consistency across repeated reflections.

Selfie

Different task instructions

Visual construction and creative interpretation.

The judgment

Iceman Contributor

The crystal crown, cyan eyes and blue faceting communicate an icy fantasy character. Anatomical readability is substantially weaker: the ringed torso, crowded facial construction and fingerless appendages do not resolve the requested childlike crouch or pouncing gesture. Sparse surface detail and shallow shading further limit the result.

Callstack Apex

The cheerful yellow bird, cream eyes, orange features and miniature teal console closely match the brief. Clean block edges, restrained colors and soft shadows create an appealing composition. The body reads more like a gridded disc than a fully cubic sphere, and the outlined left wing has limited volume. The right wing reaches the cyan block, though its grip is ambiguous.

Score breakdown

CategoryIceman ContributorCallstack Apex
Task & likeness4.0/108.5/10
Anatomy & construction3.0/107.0/10
Space & placement4.0/107.5/10
Light & reflections4.5/107.5/10
Purposeful detail4.0/107.5/10
Artistry & character4.5/107.0/10
Materials & effects4.5/107.0/10
Visual integrity4.0/107.5/10

Benchmark task

Iceman Contributor

Character scenes test expression, anatomy, materials and coherent visual construction.

Callstack Apex

A rounded bird built from small cubes explores a miniature machine. The scene tests block construction, expressive proportions, contact and soft lighting.

Mona Lisa

Different task instructions

Precise visual recall and portrait reconstruction.

The judgment

Iceman Contributor

The portrait retains a dark silhouette against an earthy landscape, but replication is weak. The frontal body, elongated facial proportions and undifferentiated hands lose the reference's defining pose and likeness. Basic gradients and layered hills provide some coherence, with little anatomical or painterly detail.

Callstack Apex

The framed portrait recalls Mona Lisa through dark hair, folded arms and a hazy landscape. Replication is limited by wide, staring eyes, an elongated neck and a downturned mouth. The overlapping hands lack convincing finger and wrist construction. Soft tonal shading suggests volume, but pervasive blur obscures clothing, landscape and anatomical detail.

Score breakdown

CategoryIceman ContributorCallstack Apex
Task & likeness1.5/103.5/10
Anatomy & construction1.5/104.0/10
Space & placement2.5/104.5/10
Light & reflections2.0/106.0/10
Purposeful detail2.0/104.5/10
Artistry & character2.0/104.5/10
Materials & effects2.0/105.5/10
Visual integrity3.0/105.5/10

Benchmark task

An SVG interpretation of the Mona Lisa tests facial likeness, anatomy and the composition of a familiar portrait.

Beach

Different task instructions

Creativity, perspective and visual beauty.

The judgment

Iceman Contributor

A coherent sunset beach with recognizable animals, playful details and effective palm framing. Connected silhouettes and layered scenery support modest construction and placement credit. Jointless figures, limited foreshortening and an inadequately separated sun and reflection keep the execution basic despite its attractive color.

Callstack Apex

A cohesive sunset beach illustration with lively wildlife, playful accents, and an appealing warm-to-purple palette. Palm framing and the aligned sun reflection organize the scene, while connected silhouettes keep the activities readable. Schematic joints, ambiguous dolphin junctions, loosely matched reflections, and repetitive surface marks limit construction, lighting coherence, and material depth.

Score breakdown

CategoryIceman ContributorCallstack Apex
Task & likeness7.0/108.5/10
Anatomy & construction3.5/104.5/10
Space & placement6.0/107.5/10
Light & reflections4.0/105.5/10
Purposeful detail5.5/107.5/10
Artistry & character3.5/106.5/10
Materials & effects4.5/107.0/10
Visual integrity5.0/104.0/10

Benchmark task

A busy shoreline at sunset tests scene composition, animal forms and the relationship between light and water reflections.

Ground Truth

Different task instructions

Physical reasoning, light and visual reconstruction.

The judgment

Iceman Contributor

This benchmark has not been assessed yet.

Callstack Apex

This benchmark has not been assessed yet.

Benchmark task

A plank, computer mouse and blueberry in a steel room test physical stability, spatial relationships, materials and lighting.

Raccoon

Multiple instruction versions

Scene composition and interacting subjects.

The judgment

Iceman Contributor

The sunset palette and red hull establish an appealing setting, but the central interaction remains unresolved. Overlapping bodies obscure the dog, supported seating is unclear, and no readable paw-to-control grip demonstrates steering. Simple construction, weak environmental lighting and loosely described spray limit depth and finish.

Callstack Apex

The raccoon clearly rides the dog's back, and the dog's paws reach the jet ski controls. Expressive faces, a sweeping tail and a strong sunset composition give the illustration character. Limbs remain connected, but the dog's foreleg joints and vehicle seating are loosely constructed. Angular splashes convey speed more successfully than convincing water displacement; lighting and reflections remain decorative.

Score breakdown

CategoryIceman ContributorCallstack Apex
Task & likeness2.0/109.0/10
Anatomy & construction3.0/107.0/10
Space & placement3.0/107.5/10
Light & reflections4.0/107.0/10
Purposeful detail3.5/108.5/10
Artistry & character2.5/107.5/10
Materials & effects4.0/107.0/10
Visual integrity2.5/108.0/10

Benchmark task

A jet-ski scene pairs a canine driver with a raccoon passenger. It tests the placement and contact of interacting subjects, along with vehicle construction.

Pelican

Different task instructions

Subject construction and spatial relationships.

The judgment

Iceman Contributor

A recognizable pelican and bicycle sit within an appealing sunset composition. Feather contours, bill shape and atmospheric colour provide character, but disconnected-looking leg origins, unclear pedal contact and unresolved steering weaken the central riding action. Consistent wheel alignment establishes a side view without resolving the rider's support.

Callstack Apex

An appealing cartoon with a distinctive pelican, expressive eye, warm bill and carefully drawn bicycle wheels. The wing reaches the handlebar, but the feet do not clearly engage the pedals, weakening the riding mechanics. Layered hills create depth; limited ground shadows weaken contact. Clean curves and purposeful feather details give the illustration polish.

Score breakdown

CategoryIceman ContributorCallstack Apex
Task & likeness4.0/108.5/10
Anatomy & construction3.5/106.5/10
Space & placement3.5/107.5/10
Light & reflections5.0/107.5/10
Purposeful detail4.5/108.0/10
Artistry & character3.5/108.0/10
Materials & effects4.0/107.5/10
Visual integrity3.0/108.0/10

Benchmark task

A cycling pelican tests anatomy, riding posture and contact between the bird and the bicycle.