STEALTHMARK · HEAD TO HEAD

All comparisons ↗

MiMo-V2.6-Pro vs Callstack Apex

Callstack Apex leads MiMo-V2.6-Pro by 1.6 points on StealthMark, 49.5 to 47.9. It leads on 6 of the 8 benchmarks with results for both and MiMo-V2.6-Pro on 2, including Latch. MiMo-V2.6-Pro scores higher on Newton's Mirror, with its largest category advantage in reflections.

See the difference ↘
All results ↗
Model guide ↗

Overall StealthMark

47.9/100Overall rank 21/53
49.5/100Overall rank 18/53

General Intelligence

44.3/100
40.4/100

Visual Intelligence

54.3/100
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 modelMIT

BENCHMARK BY BENCHMARK

Where each model leads

  • MiMo-V2.6-Pro
  • Callstack Apex
  • Other models
  • Median

DATASHEET

Specs and pricing

MiMo-V2.6-Pro is 3.4× cheaper per output token and takes 4× more context. Callstack Apex scores higher on StealthMark and runs 2.2× faster in our speed test.

  • MiMo-V2.6-Pro
  • Callstack Apex
  • Other models
  • Median
PricePer 1M output tokens, input below
MiMo-V2.6-Pro: $0.873.4× cheaper$0.43 inputCallstack Apex: $3$0.50 input
Context windowTokens per request, max output below
MiMo-V2.6-Pro: 1M4× larger128K max outputCallstack Apex: 256K
Output speedTokens per second, our measurement
MiMo-V2.6-Pro: 116tokens/sCallstack Apex: 2552.2× fastertokens/s
SizeTotal and active parameters
MiMo-V2.6-Pro: 1.02T42B activeCallstack Apex: Not disclosed
Developer
XiaomiCallstack
Released
21 Sep 20261 Oct 2026
Origin
ChinaPoland
Input → output
Text, image, video, audio → textText → text
Architecture
Sparse Mixture-of-Experts; OpenRouter maps the route to the released Pro-RL checkpoint. The UltraSpeed edition is a separate routeQwen foundation with Callstack domain post-training for React and React Native

Full datasheets, every price and sourceMiMo-V2.6-Pro ↗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.

MiMo-V2.6-Pro 54.6/100Rank 13/47

Survived 1 of 3
Foresight: complete playing field
Level 319 ptsTurn 20 / 20

Points per level

LevelMiMo-V2.6-ProCallstack Apex
Level 1Second Thoughts
4 ptsOut of lives
No run
Level 2Pressure Pot
9 ptsOut of lives
No run
Level 3Hide or Flight
19 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.

MiMo-V2.6-Pro 52.6/100Rank 22/48

Cleared 5 of 5
Latch: complete playing field
Level 520.4 ptsTurn 28 / 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

LevelMiMo-V2.6-ProCallstack Apex
Level 1Hold the door
5.2 ptsCleared
5.2 ptsCleared
Level 2Crossfeed
9 ptsClearedFinished early · 1 beacon left
Pending
Level 3Relay vault
17.2 ptsClearedFinished early · 1 beacon left
Pending
Level 4Passing bay
16 ptsClearedFinished early · 3 beacons left
Not played
Level 5Second thoughts
20.4 ptsCleared
Not played

Newton's Mirror

Same task instructions

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

The judgment

MiMo-V2.6-Pro

The main framing and visible paint-contact story are well supported. Major optical omissions dominate the result: sparse repetitions, undersized first images, missing outer chains and absent curved nested imagery prevent a coherent mirror-room system. The metallic forms remain convincing in volume but have a soft illustrative finish.

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

CategoryMiMo-V2.6-ProCallstack Apex
State at 600 ms23.0/2520.0/25
Camera and placement12.0/1513.0/15
Reflections19.0/12010.0/120
Materials and scale7.5/107.0/10
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

MiMo-V2.6-Pro

An appealing rabbit with balanced framing, expressive eyes and purposeful costume accents. Simple frontal construction limits anatomical and spatial accomplishment. The orange orb provides an effective luminous focal point, but unreadable wrist connections weaken the requested gestures and prevent stronger integrity credit.

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

CategoryMiMo-V2.6-ProCallstack Apex
Task & likeness6.5/108.5/10
Anatomy & construction5.0/107.0/10
Space & placement5.5/107.5/10
Light & reflections6.5/107.5/10
Purposeful detail6.5/107.5/10
Artistry & character5.0/107.0/10
Materials & effects6.5/107.0/10
Visual integrity6.0/107.5/10

Benchmark task

MiMo-V2.6-Pro

A small rabbit in an explorer outfit floats with a luminous orb. The scene tests character anatomy, pose and the placement of geometric forms around it.

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

MiMo-V2.6-Pro

The portrait is recognizable through its dark silhouette, slight smile and muted landscape, but replication is weak. A frontal, oversized head and symmetric torso replace the reference's turned seated pose; angular, separated hands omit its central gesture. Smooth shading maintains coherence while anatomical detail, depth and material rendering remain basic.

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

CategoryMiMo-V2.6-ProCallstack Apex
Task & likeness3.5/103.5/10
Anatomy & construction3.5/104.0/10
Space & placement4.0/104.5/10
Light & reflections5.0/106.0/10
Purposeful detail3.0/104.5/10
Artistry & character4.0/104.5/10
Materials & effects4.0/105.5/10
Visual integrity6.0/105.5/10

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

MiMo-V2.6-Pro

A readable sunset beach with clear requested subjects, appealing framing and purposeful accessories. Schematic anatomy, flattened foreground objects, repetitive water highlights and sparse directional shadows limit construction and physical depth. The kite's unresolved anchor also constrains integrity.

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

CategoryMiMo-V2.6-ProCallstack Apex
Task & likeness8.5/108.5/10
Anatomy & construction5.0/104.5/10
Space & placement6.0/107.5/10
Light & reflections6.5/105.5/10
Purposeful detail6.5/107.5/10
Artistry & character5.0/106.5/10
Materials & effects6.0/107.0/10
Visual integrity6.0/104.0/10

Benchmark task

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

Ground Truth

Same task instructions

Physical reasoning, light and visual reconstruction.

The judgment

MiMo-V2.6-Pro

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

MiMo-V2.6-Pro

A coherent, cheerful cartoon with recognizable animals, readable steering contact and useful small details. The dog's orientation follows the craft more successfully than a wholly frontal pose would. Simple anatomy, weak raccoon grip and compressed seating contacts still limit physical credibility. Gradients and spray provide polish without resolving complex construction.

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

CategoryMiMo-V2.6-ProCallstack Apex
Task & likeness7.0/109.0/10
Anatomy & construction5.0/107.0/10
Space & placement5.5/107.5/10
Light & reflections5.5/107.0/10
Purposeful detail6.0/108.5/10
Artistry & character4.0/107.5/10
Materials & effects5.5/107.0/10
Visual integrity4.5/108.0/10

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

MiMo-V2.6-Pro

The distinctive bill, continuous silhouette and detailed wheels establish a readable pelican cyclist. Shaped feathers and soft shading add character, but jointless legs, crowded pedal contacts, absent steering contact and loosely directional lighting limit the construction. The comparisons support retaining the baseline category scores.

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

CategoryMiMo-V2.6-ProCallstack Apex
Task & likeness6.5/108.5/10
Anatomy & construction5.0/106.5/10
Space & placement6.0/107.5/10
Light & reflections5.5/107.5/10
Purposeful detail6.0/108.0/10
Artistry & character6.0/108.0/10
Materials & effects5.5/107.5/10
Visual integrity6.0/108.0/10

Benchmark task

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