StitchDiag is a free, browser-based educational tool for people who use ordinary home lockstitch sewing machines and want a safer first step when a test seam looks wrong. Instead of asking a user to guess from a single symptom, StitchDiag combines a short test seam, matching photos of the front and back, and a small set of structured setup details. Users can describe the machine, fabric, needle, thread, bobbin, stitch settings, and visible symptom. The tool then describes observable clues, ranks up to three possible causes, and recommends one controlled next check. It explains what change to look for and supports a simple follow-up result such as improved, unchanged, worse, or not safe to test.
The workflow is designed for common home sewing problems including loops on the fabric back, bird nesting, thread showing on the wrong side, skipped stitches, upper or bobbin thread breaking, puckering, uneven stitch length, zigzag tunneling, and fabric-feed problems. A representative example is loops on the back of a test seam. With the machine powered off and the presser foot raised, a user may rethread the documented upper path, sew one short test seam, and compare the result. StitchDiag does not instruct users to open the machine, change internal timing, adjust electrical parts, or turn an internal bobbin-tension screw.
Safety boundaries are a core part of the product. StitchDiag does not provide a confirmed diagnosis, a repair-success percentage, a safety certification, or a promise that a machine will be fixed. It is an educational first-check tool, not a replacement for a qualified sewing-machine technician. Users are told to stop and seek qualified service if there is smoke, a burning smell, unusual heat, electrical damage, repeated needle strikes, a hard jam, persistent impact, or any need to open the machine or work on internal mechanical or electrical parts. The tool also does not claim that its suggestions are suitable for every machine or material.
StitchDiag is initially focused on English-speaking home sewers in the United States who use ordinary household lockstitch machines. It is not intended for industrial machines, sergers or overlockers, embroidery machines, or advanced internal repair. The public experience starts free and currently has no checkout, delivery, subscription, or refund promise. There are no public customer counts, testimonials, or guaranteed outcomes to report.
The product combines a lightweight web interface, structured questions, client and server image validation, a versioned safety rules engine, and optional AI-assisted image observation. Image observation is used to describe visible evidence; the safety rules and allowed-action boundaries control what guidance can be shown. When the optional observer is unavailable, the product can use a transparent rules-based fallback rather than pretending that it saw something in a photo. The design goal is not to replace sewing knowledge. It is to make the first safe check more organized, explainable, repeatable, and easier to discuss with a qualified technician when professional help is needed.
