Ebay Buy Marketing API
Browse all Ebay APIs67
AI ReadinessAI-Aware (B)67/100
Official vendor OpenAPI document · agent-readyE CommerceStorefrontoauth21 EndpointsREST
For Agents
Retrieve best-selling and merchandised eBay products by category for recommendations, deal feeds, and shopping agents. One endpoint, ranked by metric.
Use for: Get the best-selling laptops on eBay right now, List merchandised products in the Camera category, Retrieve top-selling running shoes on EBAY_US, Find all best-selling smartphones under category 9355
Not supported: Does not handle item search, full listing detail, or seller-side merchandising - use for retrieving ranked best-seller product lists by category only.
The eBay Buy Marketing API surfaces merchandised eBay products by metric - currently best-selling - so applications can recommend products that are actually moving on eBay rather than guessing from search ranking. Each merchandised product entry includes the listing reference, image, and price snapshot, ready for use in price-comparison sites, deal aggregators, and AI shopping agents. The single GET /merchandised_product endpoint accepts a category_id and metric_name and returns a ranked list, making the API simple to integrate as a discovery layer on top of the larger Browse API.
Install Jentic One Beta
Connect the Buy Marketing API to your agent
Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the Buy Marketing API, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.
Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.
1
Step 1: Jentic One Host machine
# On the machine that will host your Jentic One instance:
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Febay.com%2Fbuy-marketing" | sh2
Step 2: Agent machine
# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Febay.com%2Fbuy-marketing" | sh
jentic register # connects your agent to your Jentic One instanceJentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.
Capabilities
What an agent can do with Buy Marketing API.
Retrieve best-selling eBay products for a given category to populate recommendation widgets
Surface merchandised products with image, title, and price snapshot for price-comparison feeds
Filter merchandised results by aspect (e.g., brand, model) to narrow to a product subset
Drive shopping-agent suggestions with listings eBay actively merchandises rather than search ranking
Power deal-of-the-day feeds with category-level best-seller rotations
Use Cases
Patterns agents use Buy Marketing API for, with concrete tasks.
★ Best-seller widget for an affiliate site
Affiliate publishers call /merchandised_product with metric_name=BEST_SELLING and a leaf category_id to pull the top eBay best-sellers for that category, refreshing the widget once per hour. Each entry already includes the EPID, image URL, and current price, so the widget renders without a second Browse API roundtrip.
Call /merchandised_product with category_id=9355 and metric_name=BEST_SELLING and emit the top 10 entries as an HTML widget
Shopping-agent product suggestions
An AI shopping assistant uses Buy Marketing to suggest gifts under a user budget. The agent calls /merchandised_product for the relevant leaf category, filters by aspect_filter (e.g., brand), and returns the ranked list. Because eBay's merchandising signal is based on actual sales velocity, suggestions land closer to what shoppers are buying than raw search ranking.
Get best-selling items in category 11450, filter to brand=Nike, and return the top 5 with title and price
Deal-of-the-day rotation
Deal-aggregator sites use Buy Marketing as a category rotation source - each day a different leaf category's best-sellers headline the homepage. The single endpoint replaces multiple Browse search calls and keeps the rotation aligned with eBay's own merchandising rather than third-party trend signals.
Pick a random leaf category each day, fetch /merchandised_product, and publish the top 20 entries to the homepage
AI agent integration via Jentic
An AI shopping agent queries Jentic with 'find best selling eBay products in a category' and Jentic returns the /merchandised_product operation along with its required parameters (category_id, metric_name). The agent loads the schema, executes the call with an OAuth Application access token issued through Jentic's vault, and returns ranked product cards to the user.
Use Jentic to search 'find best selling eBay products', load /merchandised_product, and execute it for category_id 9355
Key Endpoints
1 endpoints — the ebay buy marketing api surfaces merchandised ebay products by metric - currently best-selling - so applications can recommend products that are actually moving on ebay rather than guessing from search ranking.
METHOD
PATH
DESCRIPTION
GET
/merchandised_product
Get ranked merchandised products for a category and metric (e.g., BEST_SELLING)
GET
/merchandised_product
Get ranked merchandised products for a category and metric (e.g., BEST_SELLING)
Jentic AI Readiness Score
This API is usable in Jentic One now. Its AI-readiness score against Jentic's framework shows where it stands today and where improvements would make it even easier for agents to use.
B
Buy Marketing API
- AI-Aware (B)67/100
100
Foundational Compliance69
Developer Experience & Jentic Compatibility46
AI-Readiness & Agent Experience94
Agent Usability85
Security50
AI DiscoverabilityPowered by JenticScoring Framework 1.0.0 | Scoring Engine 0.4.0
Show dimension breakdown
100
Foundational Compliance
Base layer of spec validity and structural soundness.
Grade: A+Signals: 4
99%
Lint Results
Aggregated quality score from linter diagnostics, weighted by severity.
100%
Resolution Completeness
Percentage of `$ref` references that resolve successfully.
100%
Specification Validity
Checks whether the API description parses successfully and conforms to its declared specification (e.g., OpenAPI).
100%
Structural Integrity
Structural correctness score based on schema issues using logarithmic dampening.
69
Developer Experience & Jentic Compatibility
Clarity, completeness, and ingestion readiness for developers and tooling.
Grade: B+Signals: 4
0%
Example Density
How richly the API is illustrated with examples.
100%
Example Validity
Percentage of examples that conform to their schemas.
75%
Response Coverage
Percentage of operations with complete response definitions (success, client error, server error).
100%
Tooling Readiness
Health of API ingestion, bundling, and resolution within Jentic pipelines.
46
AI-Readiness & Agent Experience
Semantic breadth, depth, and agent comprehension for AI systems.
Grade: DSignals: 4
86%
Description Coverage
Coverage of descriptions across API elements.
0%
Error Standardization
Coverage of RFC 9457 Problem Details for error responses.
100%
OperationId Quality
Coverage, uniqueness, and casing consistency of operationIds for AI inference.
0%
Summary Coverage
Coverage of summaries across operations/tags/info.
94
Agent Usability
Functional utility, complexity comfort, and AI orchestration readiness.
Grade: A+Signals: 1
94%
Complexity Comfort
Agent comfort level based on API operational and structural complexity.
85
Security
Trust, risk posture, and security compliance.
Grade: ASignals: 1
85%
Authentication Strength
Average quality of security schemes based on authentication method strength (weakest link for OAuth2).
50
AI Discoverability
Findability, semantic richness, and reasoning readiness.
Grade: C-Signals: 1
50%
Descriptive Richness
Clarity and depth of descriptions across API elements.
Score it yourself
Every API in the directory is allowlisted, so you can re-score it with no key required.
npx @jentic/api-scorecard-cli score <openapi-url>Why Jentic?
What agents get from Jentic-routed access to this vendor.
Setup
Wiring the eBay Buy Marketing API by hand means running the OAuth 2.0 client-credentials flow for the buy.marketing scope, caching the application token, and setting the category and metric parameters on each call. Through Jentic you install once, import the Buy Marketing API from the API Directory, store the client credentials once, and your agent calls it.
Permission scoping
The Buy Marketing API selects best-seller lists through query parameters like category_id and metric_name rather than URL path segments, and it exposes a single merchandised-product operation, so scope your agent to that read. Nothing beyond retrieving ranked product lists is available unless the API adds it.
Credential isolation
Your eBay OAuth client credentials are stored once, encrypted, by your own Jentic One instance, which exchanges them for a scoped token and injects it at execution time. The raw client secret never enters the agent's prompt, logs, or context.
Intent-based discovery
Agents search Jentic by intent such as 'find best selling products on eBay', and Jentic returns the /merchandised_product operation with its category_id and metric_name parameters so the agent calls the right endpoint without browsing the reference docs.
Related APIs
Alternatives and complements available in the Jentic catalogue.
FAQs
Specific to using Buy Marketing API through Jentic.
What authentication does the Buy Marketing API use?
The Buy Marketing API uses OAuth 2.0 with the Client_Credentials grant - an Application access token, not a User token. Through Jentic, the OAuth client secret sits in your Jentic One instance and the agent receives a scoped access token only for the buy.marketing scope.
Can I get best-selling products across all categories at once with the Buy Marketing API?
No. /merchandised_product requires a leaf category_id - you cannot pass a root category and get a global best-seller list. To build a cross-category leaderboard, call the endpoint per leaf category and merge the results client-side.
What are the rate limits for the Buy Marketing API?
Buy Marketing falls under eBay's Buy APIs application-level rate limits, which are issued per partner application rather than published as a fixed public number. The Developer Analytics API exposes the live remaining quota for every Buy resource - query it to see the exact limit attached to your keyset.
How do I retrieve the top-selling products in a category through Jentic?
Search Jentic for 'find best selling eBay products in a category', load the /merchandised_product operation schema, and execute it with a category_id and metric_name=BEST_SELLING. Install with pip install jentic. Get started with Jentic One, the self-hosted execution layer.
Is the Buy Marketing API free?
There is no per-call fee for production use, but the API is part of the Buy API family which requires application-level approval through eBay's developer programme. Sandbox access is available immediately on developer.ebay.com.
What metrics are supported by /merchandised_product?
The currently supported metric is BEST_SELLING. eBay reserves the metric_name parameter as an enum so additional merchandising signals can be added without breaking existing clients.
Can I limit what my agent is allowed to do with the eBay Buy Marketing API?
Yes. Because you run Jentic One yourself, your own rules decide which operations and credentials your agent may use. The Buy Marketing API exposes a single read-only operation, GET /merchandised_product, which selects best-seller lists through query parameters like category_id and metric_name rather than URL path segments, so you can scope your agent to just that ranked-product read. Retrieving ranked product lists is the only thing this API does, and your stored eBay OAuth credentials are exchanged for a scoped token and injected only at execution time.
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