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Design · head to head

PaintTool SAI vs Proto.io

P

PaintTool SAI

Design

Lightweight digital painting and illustration software for Windows

From
5500/month
Rated
-
Full reviewWebsite
Proto.io logo

Proto.io

Design

Hosted high-fidelity prototyping with device preview and no code

From
On request
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: PaintTool SAI windows-only software with no native Mac or Linux version.; Proto.io prototypes live in the vendor cloud and offline export is a higher-tier feature, so the ability to archive completed client work is a plan-level decision rather than a given.
  • They diverge on capability: PaintTool SAI covers Pressure-Sensitive Tablet Support, Proto.io covers Event and condition system.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which PaintTool SAI and Proto.io actually diverge.

Attributes where PaintTool SAI and Proto.io differ
AttributePaintTool SAIProto.io
Starting price5500/monthOn request
Pricing modelone-timePer user per month
PlatformswindowsWeb, iOS, Android

Identical on both: free tier (No), user rating (Not yet rated), category (Design).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in PaintTool SAI

  • Pressure-Sensitive Tablet Support
  • Anti-Aliased Brushes
  • 16-bit ARGB Color Channels
  • Lightweight Performance
  • Crash Data Protection

Only in Proto.io

  • Event and condition system
  • Timeline animation
  • Device preview
  • Component library
  • User testing integration
  • Design import

What people use each for

The jobs each tool is most often brought in to do.

PaintTool SAI

  • Digital illustration and manga artnot Proto.io
  • Line art and inking with pressure-sensitive pensnot Proto.io
  • Lightweight painting on lower-spec computersnot Proto.io
  • Character and concept art sketchingnot Proto.io

Proto.io

  • Running usability tests where the prototype must respond to real input rather than replay a fixed click pathnot PaintTool SAI
  • Demonstrating a form-heavy or data-driven flow to stakeholders before any code existsnot PaintTool SAI
  • Testing a mobile interaction on the physical device it is designed for, with correct gesture behaviournot PaintTool SAI
  • Validating a concept for a client who needs to feel the product, not watch a video of itnot PaintTool SAI

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

PaintTool SAI

  • Windows-only software with no native Mac or Linux version.
  • Only supports 32-bit operation, lacking modern 64-bit performance benefits.
  • Lacks the advanced brush engine customization and layer effects found in tools like Photoshop or Clip Studio Paint.
  • No cloud sync or mobile app, unlike many modern illustration tools.

Proto.io

  • Prototypes live in the vendor cloud and offline export is a higher-tier feature, so the ability to archive completed client work is a plan-level decision rather than a given.
  • Design is done elsewhere and interaction is rebuilt here, so every change to the visual design has to be reapplied by hand and the two artefacts drift apart.
  • The event and condition model is layer based, so a genuinely complex flow becomes a large tree of triggers that nobody but its author can audit.
  • Editor seats are priced individually and viewer access is limited on lower plans, so opening review to a wide stakeholder group pushes you up a tier for people who never edit anything.
  • The market standardised on Figma, so hiring people who already know Proto.io is progressively harder and every new researcher is a training cost.

Pricing, plan by plan

PaintTool SAI

5500/month
  • Standard License$5500/month
    • Perpetual license
    • All 1.x.x minor updates
    • Free upgrade path to version 2

Proto.io

On request
  • Freelancer$undefined/month
    • Single editor
    • Limited active projects
    • Standard sharing
  • Startup$undefined/month
    • Multiple editors
    • More projects
    • Team library
  • Agency$undefined/month
    • Higher project and storage limits
    • Client sharing controls
  • Corporate$undefined/month
    • Largest quotas
    • Offline export on higher tiers
    • Priority support

Which should you pick?

Choose PaintTool SAI if

  • You need pressure-sensitive tablet support.
  • You work on windows.
  • You also want anti-aliased brushes.
PaintTool SAI review

Choose Proto.io if

  • You need event and condition system.
  • You work on Web, iOS, Android.
  • You also want timeline animation.
Proto.io review

Questions people ask

Is PaintTool SAI or Proto.io better?
Neither clearly leads. PaintTool SAI starts at 5500/month and Proto.io at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, PaintTool SAI or Proto.io?
PaintTool SAI starts at 5500/month and Proto.io at On request.
Does PaintTool SAI or Proto.io run on more platforms?
PaintTool SAI runs on windows. Proto.io runs on Web, iOS, Android.
What is PaintTool SAI best used for?
PaintTool SAI is most often used for digital illustration and manga art, line art and inking with pressure-sensitive pens, lightweight painting on lower-spec computers, character and concept art sketching. Of those, digital illustration and manga art and line art and inking with pressure-sensitive pens are not what Proto.io is typically brought in for.
What can PaintTool SAI do that Proto.io cannot?
PaintTool SAI covers Pressure-Sensitive Tablet Support, Anti-Aliased Brushes, 16-bit ARGB Color Channels, Lightweight Performance. Proto.io covers Event and condition system, Timeline animation, Device preview, Component library.

Answered from the vendors’ own pages

PaintTool SAI: Is there a free trial for PaintTool SAI?

Yes, PaintTool SAI offers a 31-day free trial with full functionality before requiring purchase of a license.

Source
Proto.io: Can it replace Figma?

No. It has no design system or file-handoff role. It sits alongside Figma for the prototypes Figma cannot express.

PaintTool SAI: What does the license cover?

The one-time 5,500 JPY purchase provides a perpetual license covering all minor updates within version 1.x.x; a major version 2 upgrade is offered for free.

Source
Proto.io: What happens to prototypes if we stop paying?

They stop being accessible unless you have exported them, and offline export is restricted to higher plans, so plan archiving before you cancel.

PaintTool SAI: What operating systems are supported?

PaintTool SAI runs on Windows XP through Windows 11, but only in 32-bit mode, requiring at least a 450MHz Pentium processor and 256MB of RAM.

Source
Proto.io: Is it worth learning now that InVision has gone?

If your work is usability research on conditional flows, yes. If you need click-through demos of static screens, Figma already does that at no extra cost.

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