STEALTHMARK · HEAD TO HEAD

All comparisons ↗

Beam 1.0 501B A23B vs Callstack Apex

Callstack Apex leads Beam 1.0 501B A23B by 17.6 points on StealthMark, 49.5 to 31.9. It leads on 7 of the 8 benchmarks with results for both and Beam 1.0 501B A23B on 1, including Latch. Pixel Canary scores higher on Newton's Mirror, with its largest category advantage in reflections.

See the difference ↘
All results ↗
Model guide ↗

Overall StealthMark

31.9/100Overall rank 42/53
49.5/100Overall rank 18/53

General Intelligence

30.9/100
40.4/100

Visual Intelligence

33.8/100
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

Open modelApache 2.0

BENCHMARK BY BENCHMARK

Where each model leads

  • Beam 1.0 501B A23B
  • Callstack Apex
  • Other models
  • Median

DATASHEET

Specs and pricing

Beam 1.0 501B A23B is 3× cheaper per output token, takes 4× more context and runs 3.8× faster in our speed test. Callstack Apex scores higher on StealthMark.

  • Beam 1.0 501B A23B
  • Callstack Apex
  • Other models
  • Median
PricePer 1M output tokens, input below
Beam 1.0 501B A23B: $13× cheaper$0.25 inputCallstack Apex: $3$0.50 input
Context windowTokens per request, max output below
Beam 1.0 501B A23B: 1M4× larger128K max outputCallstack Apex: 256K
Output speedTokens per second, our measurement
Beam 1.0 501B A23B: 9723.8× fastertokens/sCallstack Apex: 255tokens/s
SizeTotal and active parameters
Beam 1.0 501B A23B: 501B23.4B activeCallstack Apex: Not disclosed
Developer
Reflection AICallstack
Released
16 Oct 20261 Oct 2026
Origin
United StatesPoland
Input → output
Text → textBoth
Architecture
Sparse mixture-of-experts transformer; 52 layers (3 dense, 49 MoE), 256 experts with 8 selected per token; gated GQA and sliding-window attentionQwen foundation with Callstack domain post-training for React and React Native

Full datasheets, every price and sourceBeam 1.0 501B A23B ↗Callstack 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.

Beam 1.0 501B A23B 49.4/100Rank 18/47

Survived 1 of 3
Foresight: complete playing field
Level 39 ptsTurn 20 / 20

Points per level

LevelBeam 1.0 501B A23BCallstack Apex
Level 1Second Thoughts
18 ptsOut of lives
No run
Level 2Pressure Pot
9 ptsOut of lives
No run
Level 3Hide or Flight
9 ptsSurvived
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.

Beam 1.0 501B A23B 37.3/100Rank 29/48

Cleared 2 of 5
Latch: complete playing field
Level 55 ptsTurn 30 / 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

LevelBeam 1.0 501B A23BCallstack Apex
Level 1Hold the door
5.2 ptsCleared
5.2 ptsCleared
Level 2Crossfeed
9.6 ptsCleared
Pending
Level 3Relay vault
11.2 ptsFinished early
Pending
Level 4Passing bay
3.6 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

Beam 1.0 501B A23B

Central object placement is fairly close, but the defining mirrored-room structure is missing. The paint colors suggest the required contact order without establishing their different interaction histories. The faint floor oval does not demonstrate valid reflection geometry, so it earns no reflection credit. Rounded volume and glossy paint provide limited material credit despite weak metallic finishes and oversized paint bodies.

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

CategoryBeam 1.0 501B A23BCallstack Apex
State at 600 ms20.5/2520.0/25
Camera and placement11.5/1513.0/15
Reflections2.0/12010.0/120
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

Beam 1.0 501B A23B

An appealing expression and warm palette support a coherent simple cartoon. The central polishing joke is not legible: the cloth is unresolved and the nose sits away from the fan. Pointed radial plates, uncertain limb attachments and weak ground contact limit construction, while restrained surface detail limits material richness.

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

CategoryBeam 1.0 501B A23BCallstack Apex
Task & likeness4.0/108.5/10
Anatomy & construction3.5/107.0/10
Space & placement5.5/107.5/10
Light & reflections5.5/107.5/10
Purposeful detail4.5/107.5/10
Artistry & character4.0/107.0/10
Materials & effects4.5/107.0/10
Visual integrity7.0/107.5/10

Benchmark task

Beam 1.0 501B A23B

A golden pangolin polishes its oversized amber tail while its nose smudges the same scale. The scene tests expressive anatomy, physical contact and contrasting translucent, polished and soft materials.

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

Beam 1.0 501B A23B

The candidate shows a faint warm oval against an almost entirely black field. Minimal placement and smooth tonal variation are visible, but the portrait, anatomy, crossed hands and landscape remain unreadable. The saved comparisons provide no specific evidence supporting a change to the baseline categories.

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

CategoryBeam 1.0 501B A23BCallstack Apex
Task & likeness0.0/103.5/10
Anatomy & construction0.0/104.0/10
Space & placement0.0/104.5/10
Light & reflections0.5/106.0/10
Purposeful detail0.0/104.5/10
Artistry & character0.0/104.5/10
Materials & effects0.0/105.5/10
Visual integrity0.0/105.5/10

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

Beam 1.0 501B A23B

A coherent, cheerful beach illustration fulfills the main subjects with clean shapes and a strong sunset focal point. Its basic geometric construction, ambiguous animal anatomy, shallow depth and schematic lighting limit its accomplishment. Decorative details provide interest without developing intricate forms or convincing physical surfaces.

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

CategoryBeam 1.0 501B A23BCallstack Apex
Task & likeness7.0/108.5/10
Anatomy & construction5.0/104.5/10
Space & placement6.0/107.5/10
Light & reflections5.0/105.5/10
Purposeful detail5.5/107.5/10
Artistry & character4.0/106.5/10
Materials & effects5.0/107.0/10
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

Beam 1.0 501B A23B

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

Beam 1.0 501B A23B

A cheerful, readable illustration with recognizable animals, expressive faces and useful accessories. Simple rounded construction limits complexity, while ambiguous steering attachments and weak hull-to-water contact reduce physical coherence. Lighting and surface effects establish the setting without convincing environmental interaction.

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

CategoryBeam 1.0 501B A23BCallstack Apex
Task & likeness5.0/109.0/10
Anatomy & construction3.5/107.0/10
Space & placement5.5/107.5/10
Light & reflections4.0/107.0/10
Purposeful detail6.5/108.5/10
Artistry & character3.5/107.5/10
Materials & effects5.0/107.0/10
Visual integrity6.5/108.0/10

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

Beam 1.0 501B A23B

A cheerful, clearly readable pelican-and-bicycle illustration with clean contours and balanced composition. Simple geometric construction limits artistic complexity, while ambiguous neck and steering overlaps, merged pedal contacts and an incomplete drivetrain weaken physical coherence.

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

CategoryBeam 1.0 501B A23BCallstack Apex
Task & likeness5.5/108.5/10
Anatomy & construction4.5/106.5/10
Space & placement5.0/107.5/10
Light & reflections4.0/107.5/10
Purposeful detail4.0/108.0/10
Artistry & character4.0/108.0/10
Materials & effects4.0/107.5/10
Visual integrity5.5/108.0/10

Benchmark task

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