What are Amazon Backend Search Terms?
Amazon backend search terms are hidden keywords that only Amazon's algorithm can see — not customers. Despite being invisible, they are one of the most powerful tools for expanding search visibility and are frequently underutilized by brands. This guide explains what they are, how they work, and how to fill them effectively.
What are Backend Search Terms?
Backend search terms are keywords you enter in the hidden fields of a product listing in Seller Central (under the "Keywords" tab when editing a listing). Unlike your title, bullets, and description which customers read, backend keywords are only used by Amazon's A9 search indexing algorithm. They allow you to include relevant search terms that do not fit naturally in your visible content.
Why Backend Search Terms Matter
Amazon's algorithm indexes your listing for every keyword it finds associated with the ASIN — from the title, bullets, description, attributes, and backend keywords. If a shopper searches a term that is not anywhere in your content or backend, your product will not appear for that search. Backend keywords let you cover variations, synonyms, competitor-adjacent terms, and common misspellings without cluttering your customer-facing copy.
Backend Search Term Field Limits
The Subject Keywords field in Seller Central allows up to 250 bytes (roughly 250 characters). This is measured in bytes, not characters — special characters and spaces between words both count. Amazon's guidance is clear: do not use commas or punctuation (unnecessary and wastes space), do not repeat words already in your title or bullets, do not include brand names of competitors.
Amazon measures the backend field in bytes, not characters. Standard ASCII characters (letters, numbers, spaces) count as 1 byte each. Special characters (accented letters, non-standard punctuation) may count as 2 bytes. This means you can fit roughly 250 standard keywords and spaces. The practical implication: stick to plain text, no punctuation, just words separated by spaces. Every byte saved on a comma is another character of keyword coverage.
What to Include in Backend Keywords
- Spelling variations and common misspellings your customers might type
- Synonyms — different words buyers use for the same product type
- Related use cases not prominently featured in visible content
- Size and material variations
- Long-tail phrases that are relevant but too specific for the title
- Abbreviations and alternate product names
What to Avoid in Backend Keywords
- Repetition of words already in your title — no indexing benefit, wastes space
- Competitor brand names — violates Amazon policy and can result in listing suppression
- Irrelevant keywords — stuffing unrelated terms can harm relevance signals over time
- Commas and punctuation — Amazon's parser handles spaces correctly, punctuation wastes character count
- Statements or phrases — single keywords or two-word combinations work better than full phrases
How to Research Backend Keywords
- Use Amazon autocomplete: type your primary keyword in Amazon's search bar and capture all suggested completions
- Analyze competitor listings for keywords in their visible content that are relevant but absent from yours
- Use third-party tools like Helium 10 (Magnet), Jungle Scout, or DataDive to identify high-volume related keywords
- Review customer reviews and Q&A on your listing and competitors' listings — the language customers use to describe the product and their needs is the language they also use to search
Frequently Asked Questions
Backend search terms are keywords you enter in the hidden fields of a product listing in Seller Central under the Keywords tab when editing a listing. Unlike your title, bullets, and description which customers read, backend keywords are only used by Amazon's A9 search indexing algorithm. They allow you to include relevant search terms that do not fit naturally in your visible content.
Amazon's algorithm indexes your listing for every keyword it finds associated with the ASIN — from the title, bullets, description, attributes, and backend keywords. If a shopper searches a term that is not anywhere in your content or backend, your product will not appear for that search. Backend keywords let you cover variations, synonyms, competitor-adjacent terms, and common misspellings without cluttering your customer-facing copy.
The Subject Keywords field in Seller Central allows up to 250 bytes (roughly 250 characters). This is measured in bytes, not characters — special characters and spaces between words both count. Do not use commas or punctuation, do not repeat words already in your title or bullets, and do not include competitor brand names.
Include spelling variations and common misspellings, synonyms and different words buyers use for the same product, related use cases not prominently featured in visible content, size and material variations, long-tail phrases that are relevant but too specific for the title, and abbreviations and alternate product names.
Avoid repeating words already in your title (no indexing benefit, wastes space), competitor brand names (violates Amazon policy), irrelevant keywords (stuffing unrelated terms can harm relevance signals), commas and punctuation (Amazon's parser handles spaces correctly), and full phrases or sentences (single keywords or two-word combinations work better).
Use Amazon autocomplete by typing your primary keyword in Amazon's search bar and capturing all suggested completions. Analyze competitor listings for keywords in their visible content relevant but absent from yours. Use third-party tools like Helium 10 Magnet, Jungle Scout, or DataDive to identify high-volume related keywords. Review customer reviews and Q&A — the language customers use to describe the product is the language they also use to search.
About Perfality
Perfality is an end-to-end ecommerce and marketplace management agency trusted by 75+ global CPG and DTC brands including Spectrum Brands, Kenneth Cole, Black+Decker, Stella & Chewy's, and Galderma. With 8 years of hands-on experience and a 100+ specialist team based in Jaipur, India, Perfality helps brands grow on Amazon, Walmart, Chewy, Petco, and other major marketplaces through listing optimization, A+ content, PPC management, account operations, chargeback recovery, and data intelligence. Learn more at www.perfality.com.
Perfality's content team builds keyword-rich backend search term sets for 75+ global CPG brands. Let's audit your catalog and maximize your indexing coverage.
