Sizing costs brands billions.
FitSpec fixes it.

Measurement infrastructure for apparel brands. Configure size charts, deploy sizing recommendation APIs, and reduce fit-related returns — without hiring a fit team.

B2B SaaS Apparel Tech Launching 2026

There's no standard sizing in apparel. A size 10 from one brand fits completely differently in another. Brands manage this with spreadsheets, siloed fit tech, and manual guesswork. Returns pile up. Customers leave frustrated.

FitSpec is measurement infrastructure — the config layer that makes sizing tools actually work.

What FitSpec does

Size Chart Configuration

Build and maintain accurate size charts for tops, bottoms, shoes, and specialty apparel. Define measurements, grading rules, and tolerance ranges in one place.

Sizing Recommendation API

Embed a sizing recommendation widget on your product pages. Takes customer measurements, matches against your specs, returns the right size — every time.

Returns Intelligence

Connect your return data to fit analysis. See which styles, sizes, and body types are causing the most problems — and get specific recommendations to fix them.

Multi-Brand Scaling

Manage sizing across multiple product lines and manufacturers. One config layer that stays consistent as your catalog grows.

How it works

Three steps from broken sizing to consistent fit.

Upload garment specs

Input your size charts and garment measurements directly, or connect to your PIM system via API. Define the key measurements that matter for each product category.

Configure recommendation rules

Set how customer input maps to your size chart. Adjust tolerance ranges, fit preferences (tight / regular / loose), and category-specific logic.

Deploy and iterate

Embed the FitSpec widget on your product pages or call the API from your frontend. Track returns and refine specs over time as you gather real fit data.

API Reference Preview

FitSpec's recommendation engine, exposed as a clean REST API.

POST /v1/recommend

{
  "garment_id": "tops-001",
  "customer_measurements": {
    "height_cm": 175,
    "weight_kg": 72,
    "chest_cm": 98,
    "preferred_fit": "regular"
  },
  "size_chart": {
    "XS": { "chest_cm": { "min": 86, "max": 91 } },
    "S":  { "chest_cm": { "min": 91, "max": 97 } },
    "M":  { "chest_cm": { "min": 97, "max": 102 } },
    "L":  { "chest_cm": { "min": 102, "max": 107 } },
    "XL": { "chest_cm": { "min": 107, "max": 112 } }
  }
}

// Response
{
  "recommended_size": "M",
  "confidence": 0.94,
  "alternatives": ["S", "L"],
  "fit_notes": "Regular fit — chest measurement lands in middle of M range"
}

Built for the fit technicians, product developers, and e-commerce engineers who are already doing this work — just without the right tools.

FitSpec is B2B infrastructure. Not a consumer app. Not a chatbot. A config layer that makes sizing work.

Sizing costs brands billions. FitSpec fixes it.