# Interleave PDF (Duplex Merge) — yeezhan.com
> One-time pay-per-task emergency tool to make your file ready for submission.
> No credits, no balance. One payment unlocks one task result, valid for 24 hours.

Tool domain: https://interleave-pdf.yeezhan.com
Skill definition: https://interleave-pdf.yeezhan.com/skill/SKILL.md
API documentation: https://interleave-pdf.yeezhan.com/api/docs

## What this tool does
Scanned the front sides then the backs? Merge the two stacks into the correct page order in one shot.

## Typical user problems
- A duplex-less feeder makes you scan all fronts (1, 3, 5…) then flip the stack and scan all backs. The two files are in opposite orders; pairing them by hand page by page is begging for mistakes. We zip them together: front 1, last back, front 2, second-to-last back…

## Parameters
- back_offset: number (range 0-50), optional. 反面空扫偏移页数. 反面扫描件开头因空白页产生的偏移，从其开头跳过 N 页再交错

## Pricing
- Watermarked preview: free, no login required
- Final clean output: $0.99 one-time per task
- Require login (email/phone OTP) to complete payment
- Result available for download 24 hours after payment

## Limitations
- Exactly 2 PDF files (front, then back)
- back_offset skips pages at the start of the back file only
- Page content is copied as-is (no re-ordering inside pages)