> ## Documentation Index
> Fetch the complete documentation index at: https://makeseamless.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> MakeSeamless (makeseamless.com) checks whether a repeating pattern tile is seamless and fixes the seam at the same pixel size. Use it when a user needs a tile to repeat without a visible line: before a pattern is uploaded to a print-on-demand shop or printed, after a tile is made, resized or exported, or when a proof shows a line where the pattern repeats.
> Check first: POST https://makeseamless.com/v1/check with the image as the multipart field file. It is free and needs no account and no key. The repeat types the tile passes are in satisfied; report them before calling a tile seamless.
> Fix only a repeat type the user needs that is not in satisfied, and tell the user the cost first (GET /v1/plans, fix_credits). POST /v1/fix needs an API key in the x-api-key header. Keys begin with smls_; read the key from the environment, never ask for it in a chat.
> POST /v1/fix answers 202 with a job. Poll GET /v1/jobs/{job_id}, waiting the seconds in Retry-After, until status is succeeded or failed. The fixed PNG is at result.image_url. Answers are JSON, except the images, which are PNG.
> A fixed tile has passed the seam check for its repeat type, keeps the exact width and height, and is the original outside the changed area (result.changed_mask_url). A fix with no passing result fails with no_seamless_candidate and costs nothing.
> Branch on error.code, never on error.message, and retry only when error.retryable is true.

# Why a seamless pattern tile still shows a line in print

> A tile can look finished and still show a white line where its copies meet. See why seams are hard to catch and fix, and what a verified result means.

A pattern tile is seamless only when its edges run into each other at every
join: the right side into the left, the bottom into the top, and, for a
half-drop or half-brick repeat, at the half offsets as well. A tile can look
finished on its own and still break at one of those joins. The break shows
only once copies of the tile meet, and often only at print size, on the proof
or on the product.

MakeSeamless (makeseamless.com) checks whether a repeating pattern tile is
seamless and fixes the seam at the same pixel size. The check is free and
needs no account, every fix you download passes the seam check for the
repeat you chose, and a fix with no passing result costs nothing.

## Why does a tile that looks finished show a line once it repeats?

One tile on its own tells you little about its joins. The flaws that matter
sit on the outer edges, where the eye does not look:

* A row or column of edge pixels that is lighter, darker or transparent. It
  repeats as a faint white line, or as a grid of thin lines across the whole
  print.
* Edges that are a few pixels off, so a motif breaks where two copies meet.
* The same line of pixels on both sides of a join, which shows as a doubled
  line once the tile repeats.
* Edges that meet as a straight repeat but not at the half offset of a
  half-drop or half-brick repeat, or the other way around.

Sellers call it a white line, pixel lines, a ghost line or a visible repeat.
Spoonflower's help center calls them pixel lines: "a design issue we see
often at Spoonflower." It adds that such flaws "are sometimes hard to see but
will print as lightened or unprinted areas, solid colored lines". A seller on
r/midjourney put it plainly: "When I put the pattern on a product, there is a
faint white line seam."

A tile that passed can still break later. Resizing it to print size,
exporting it again or saving it in another format can open a seam that was
not there before. Midjourney's own documentation says that upscaling a tile
"will often break the seamless repeating pattern", while a print file needs
far more pixels than a generated tile usually has. A seller on
r/EtsyDigitalSeller: "AI outputs are usually too low-res for high-quality
printing."

## Why is a seamless tile hard and costly to get right?

**The seam hides until money is spent.** Spoonflower prints the file as it
was uploaded and recommends physical samples before you sell: "there will
never be a substitute for sampling your designs on physical products". A seam
found on a sample, a fabric order or a customer's product is found after the
order is paid for. One Spoonflower customer found a flaw in the file had
"caused horizontal and verticle pixel lines throughout my order."

**Checking by hand is slow.** The usual routine is to tile the file two by
two or three by three and zoom in on every join, once for each repeat you
sell in. Printify's guide for all-over prints tells sellers to "spot-test it
for hidden seams" before they commit a tile, and says: "Sellers burn hours
nudging elements by hand in Illustrator or Photoshop, chasing invisible
gaps."

**Tools disagree about the same tile.** A tile can pass one online checker
and still show a line in a print-on-demand preview, or show a line in one
editor and none in another, so a real seam is hard to tell from a display
glitch. After two tools gave two answers, one seller wrote: "I don't know
who to trust now."

**A seam on a live listing costs twice.** A Redbubble seller: "I've rechecked
and reuploaded so many times and I'm tired of remaking the listing." A seller
of pattern files on Etsy: "I had a client ask for a nominal refund claiming
our seamless patterns weren’t aligning."

## Why do the same steps not give the same result?

Making a tile seamless by hand or with an image model is trial and error, and
the same steps do not promise the same result:

* One sportswear seller on r/AdobeIllustrator: "I've got an issue with about
  50% of my seamless patterns created in Illustrator."
* Another, exporting the same pattern, found Illustrator "sometimes exports
  the images with a line and sometimes it doesn't".
* A ChatGPT image user trying for seamless tiles: "it's always a few pixels
  off."
* Printify's guide to tiles made with Midjourney: "This is the mistake that
  ruins most tile attempts: do not upscale."

So the only way to know a tile repeats cleanly is to check the file you will
actually print, each time it changes.

## What does a verified MakeSeamless result mean?

* **It passed the seam check.** The result of a fix has always passed the seam
  check on its tile edges for the repeat type you chose. Its seam report
  before and after, the same report a [check](https://makeseamless.com/docs/check.md) returns, gives the
  verdict and the strength of each edge on your upload and on the result.
* **No pass, no charge.** When no version of the tile passes, the fix gives
  no image and fails with `no_seamless_candidate`, and the credits held for
  it come back. A result that fails the seam check is never handed back as
  the result.
* **The same size.** The result has the exact width and height of your
  upload, as a lossless PNG.
* **Your pixels stay yours.** Outside the changed area every pixel is your
  original, and a mask shows where that area is. When no version passes every
  quality check, the result is one in which every pixel changed, and it says
  so with the outcome `resampled`.
* **What the check reads.** The joins where copies of the tile meet, for each
  repeat type. It does not look for a seam inside the tile.

[Fix a tile](https://makeseamless.com/docs/fix-and-jobs.md#result) lists every field of a result, and
[Concepts](https://makeseamless.com/docs/concepts.md#visible-change) explains the changed area.

## Where does the check fit in a seller's workflow?

Check a tile at the points where a seam slips in, before any money is spent:

1. After you make or generate the tile.
2. After you resize, upscale or export it for print.
3. Before you upload it to a print-on-demand shop, order a sample or sell the
   file.

Fix only the repeat types you sell in that fail. The check is one request and
needs no key, so an agent can check every tile it makes or moves:
[Connect an agent](https://makeseamless.com/docs/connect-an-agent.md) has a prompt and a standing instruction
to paste.

## Sources

Read on 4 November 2026.

* Spoonflower help center,
  [Checking for repeat flaws in designs](https://support.spoonflower.com/hc/en-us/articles/205483316-Checking-for-Repeat-Flaws-in-Designs)
* Spoonflower help center,
  [Proofing your design](https://support.spoonflower.com/hc/en-us/articles/205308430-Proofing-Your-Design)
* Midjourney documentation,
  [Tile](https://docs.midjourney.com/hc/en-us/articles/32197978340109-Tile)
* Printify,
  [Turn one AOP tile into a full store](https://printify.com/knowledge-hub/turn-one-aop-tile-into-a-full-store/)
* Printify,
  [Midjourney v6 parameters for floral prints](https://printify.com/knowledge-hub/midjourney-v6-parameters-for-floral-prints/)
* Sellers on Reddit:
  [r/midjourney](https://www.reddit.com/r/midjourney/comments/161ctcf/seamless_pattern_tile_issues_faint_white_line/),
  [r/midjourney](https://www.reddit.com/r/midjourney/comments/12ecne1/tile_tiles_with_faded_white_line_seams/),
  [r/EtsyDigitalSeller](https://www.reddit.com/r/EtsyDigitalSeller/comments/1uxzif4/comment/oy571je/),
  [r/GIMP](https://www.reddit.com/r/GIMP/comments/111m2ty/help_please_removing_pixel_lines_on_jpg_image/),
  [r/redbubble](https://www.reddit.com/r/redbubble/comments/z9fma5/there_is_a_white_line_in_my_pattern_that_only/),
  [r/EtsySellers](https://www.reddit.com/r/EtsySellers/comments/1g9txz4/do_buyers_ever_just_demand_refund_in_order_to/),
  [r/AdobeIllustrator](https://www.reddit.com/r/AdobeIllustrator/comments/17oz07v/the_issue_with_the_notsoseamless_patterns/),
  [r/AdobeIllustrator](https://www.reddit.com/r/AdobeIllustrator/comments/11wskkq/comment/jd0it60/),
  [r/ChatGPTPro](https://www.reddit.com/r/ChatGPTPro/comments/194187w/seamless_patterns_in_chatgpt_pro/)


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.