The 250-Byte Rule

Amazon's backend search terms field has a 250-byte limit (roughly 250 characters). Exceeding it means Amazon ignores the entire field — not just the overflow.

What to Put in Backend Keywords

✅ Synonyms your customers use but you don't repeat in the listing

✅ Spanish/multilingual terms (e.g., yoga mat → "alfombrilla yoga")

✅ Abbreviations and alternative spellings (colour / color)

✅ Use cases not covered in bullets

✅ Complementary product keywords (e.g., "replacement for brand X")

❌ Don't repeat exact phrases already in your title or bullets — Amazon already indexes those

❌ No competitor brand names — TOS violation

❌ No subjective claims ("best", "cheapest")

❌ No commas or punctuation — space-separated only

How to Find Backend Keywords

  1. Use Reverse ASIN on top 3 competitors in niche.ltd
  2. Filter for keywords ranking 50–200 (too competitive for main listing, great for backend)
  3. Export and select terms not already in your frontend content
  4. Prioritize 200–3,000 monthly searches — high enough to matter, low enough to be discovered

Checking Indexation

Use niche.ltd's Index Checker to confirm Amazon indexed your backend keywords within 24–72 hours of updating.