For a “best free tool,” I’d actually say: there isn’t one tool, there’s a stack. And I kinda disagree with @kakeru on one subtle point: relying too heavily on any single external tool (even Helium 10 on a free plan) can mislead you if you don’t sanity‑check with actual marketplace behavior.
Here are a few different free angles you can add on top of what was already shared:
- Use Amazon’s own ad console as a pseudo keyword tool
If you’re running even tiny PPC budgets:
- Create an automatic campaign for your main product.
- Let it run a few days to a week (even at $2–$5/day).
- Go to the search term report and pull what actually got impressions and clicks.
This gives you real buyer phrases tied to your ASIN, which beats guesswork.
You can then: - Promote the converting terms into exact/phrase campaigns.
- Add non‑converting but high spend terms as negatives.
Free in the sense that the “tool” is free, you just pay ad spend.
- Amazon “Categories & filters” mining
A lot of people ignore the left sidebar and filter tags:
- Search your main keyword.
- Look at the category path, subcategories, and filter labels (material, size, style, usage).
- Many of those filter labels are actually hidden long‑tail modifiers buyers use, like “for small kitchen,” “for thick hair,” “travel size,” etc.
These might not show in autocomplete, but they are powerful for longtail phrases and backend keywords.
- Global marketplaces cross‑check
If you sell in US, quickly check:
- Amazon UK / DE / CA etc with the same seed keyword.
Sometimes new angles or use cases pop up in autocomplete and in the top titles there that are not yet saturated in the US. I’ve pulled some very nice longtails this way like “for rental property” or “for camper van” that didn’t show in US suggestions at first.
- Google is not totally useless for Amazon
Yes, most “free” tools are focused on Google, but you can still exploit that:
- Use Google Keyword Planner just to find “use cases” and “modifier” words around your product.
- Then plug those modifiers back into Amazon search to see if they actually exist as phrases there.
Example: Google shows “for arthritic hands” for your product type. Then you type “[product] for arthritic hands” in Amazon and see if: - It autocompletes.
- It has relevant results with good BSRs.
If yes, it’s now a meaningful Amazon keyword, regardless of Google origin.
- Review & Q&A mining (super underused)
Pick 5–10 top competitors and:
- Scan reviews and Q&A for repeated wording buyers use.
You’re not just looking for pain points, but actual phrases that sound like search queries: - “for elderly parents,” “for tiny apartments,” “does this fit a 32oz bottle,” etc.
These are gold for: - Bullet copy
- Long‑tail backend keywords
- PPC exact match tests
And you don’t need any paid tool to do it, just patience and Ctrl+F for recurring words.
- Use a “reverse funnel” spreadsheet
@kakeru talked about relevance scoring, which I agree with. Where I’d tweak it:
Instead of starting with search volume, start with intent category:
- “Main product name”
- “Problem / pain”
- “Use case / audience”
- “Feature / material”
Put each keyword into one of those buckets first. Then within each bucket, mark: - Title-worthy
- Bullet-worthy
- Backend-only
This keeps you from chasing high-volume vanity terms and forgetting the super specific money keywords like “for kids with sensory issues” that might never top a volume chart but convert far better.
- Real free “tool”: your own test listings
This sounds dumb, but:
- Put your main 5–10 core keywords in title/bullets.
- Rotate secondary long‑tail keywords in description/back-end every 2–3 weeks.
- Track which phrases start showing your ASIN in search (you can spot this just by searching them in Amazon and see where you show up).
You’re basically using Amazon’s indexing behavior as your keyword lab. Nothing to “pay” for here except time.
If you want a single answer to “what’s the best free keyword research tool for Amazon?” I’d phrase it like this:
- The best “tool” is Amazon’s own data:
- Autocomplete
- Search term reports
- Brand Analytics if you have it
- Reviews & Q&A
- Category filters
Everything else (Helium, JS, etc.) is just a temporary crutch to speed things up. Free plans are annoying and limited, but if you build a good workflow around Amazon’s own signals, you won’t be stuck when a free tier gets nerfed or your trial expires.
If you share your niche, people here can probably throw a couple of specific keyword angles at you too.