Foundations
Part of Drawing the boundary around a marketplace seller's job before sizing the market
Manual, buyer-built, hosted or managed marketplace operations, compared by failure mode
How the four marketplace seller software business models (manual, buyer-built, hosted and managed) compare on work, evidence, failure and exit.
Four marketplace seller software business models can solve the same job in different ways: retain a manual process, build a buyer-owned connection, buy a hosted tool or contract a managed service.
This comparison uses one unit throughout: one accepted cycle in which an England merchant changes an authorised product record, updates stock, receives an order, reconciles a refund and exports the history.
Worked example: a seller edits a product title and price, stock falls from 10 to 9, an order arrives, then one unit is refunded and stock returns to 10. The export shows each step against the same product, order and refund identifiers.
What to take away
- No route wins without evidence from the merchant's catalogue, permissions, order volume, failure history and exit needs.
- Each route fails in a different placeon people, on interfaces, on plan limits or on control of access.
- Responsibilities do not move as a block, so VAT mapping and data control stay with the merchant.
- The route that passes every gate at an acceptable verified whole-life cost is eligible for procurement.
Common case and evidence fields
The seller owns the commercial decision and the marketplace account. One catalogue is in scope. Record product identifier, evidence source, listing version, available quantity, order identifier, payment state, cancellation, return, refund, dispute and settlement. The outcome is a correctly reconciled cycle with an auditable exception route, not revenue or faster growth.
GOV.UK's online-selling guidance sets out information and ordering controls for online sellers. OPSS product-safety guidance directs businesses to obligations tied to their role and product. Those gates apply to all four routes. A successful data transfer cannot substantiate a product or cure missing seller information.
Like-for-like comparison
Who performs the work
- Current manual process
- Authorised merchant staff
- Buyer-built connection
- Merchant developers or contracted build team
- Hosted service
- Contracted software supplier
- Managed service
- External operator using agreed systems
Main dependency
- Current manual process
- Documented hand-offs and marketplace interface
- Buyer-built connection
- Marketplace interface and buyer-maintained code
- Hosted service
- Exact service edition, integration and supplier operations
- Managed service
- People, approvals, account access and service contract
Evidence to obtain
- Current manual process
- Timestamped change, second-person check and exception log
- Buyer-built connection
- Versioned mapping, test results, access register and maintenance owner
- Hosted service
- Contract, data flow, support scope, change notice and export format
- Managed service
- Named approvers, activity log, escalation route and continuity plan
Exit test
- Current manual process
- Reproduce the complete record outside personal files
- Buyer-built connection
- Disable credentials and restore from buyer-held export
- Hosted service
- Import a complete export into a controlled destination
- Managed service
- Revoke access and transfer work without losing history
The comparison leaves charges blank. A supplier fee, developer labour and merchant review time use different units. The buyer should record currency, VAT basis, period, quantity, term and exclusions before calculating whole-life cost.
Typical hosted tools include Linnworks, ChannelAdvisor, Veeqo and Sellbrite. Managed delivery is often provided by ecommerce agencies, marketplace consultancies or Amazon SP-API integration partners.
Hosted plans are usually quoted per month and tiered by orders, channels and users. Entry plans are often advertised in the tens of pounds per month. Implementation is quoted as a one-off project fee, and managed retainers are quoted monthly or per order and can reach thousands of pounds per year.
A worked whole-life cost for a 24-month term adds subscription months, implementation, merchant review hours at the merchant's own rate, VAT and exit cost.
Evidence fields to record
- Product identifier
- Evidence source
- Listing version
- Available quantity
- Order identifier
- Payment, cancellation, return, refund, dispute, settlement
Responsibilities do not move as a block
HMRC's collection on goods sold through online marketplaces shows that VAT treatment can depend on seller status, customer, goods and location. A managed operator cannot decide those facts by reading a settlement file. The accountant and VAT adviser own the mapping.
Customer and staff data require a separate route. The ICO's final storage and access guidance addresses device storage and access technologies. The merchant must still document purposes, parties and configuration. The contract should state who can access what, but legal wording is not proof of actual control.
NCSC secure-service guidance supports checking identity, logging, monitoring and incident response. Apply the same synthetic access-removal and recovery test to every route. Do not award a compensating score if credentials cannot be revoked or a full history cannot be exported.
Choose by failure mode
Each route has a characteristic failure mode, and a route fails the test when that mode is credible for this catalogue:
- Current manual processfails when the cycle rests on one person, when the evidence sits in a mailbox or spreadsheet that cannot be exported, and when review time grows with order volume.
- Buyer-built connectionfails when a marketplace interface changes and nobody owns the maintenance, when channel mappings drift apart, and when the builder leaves without documentation.
- Hosted servicefails when the plan's order, channel or user limits are reached, when the exit test shows the order history cannot be exported in a usable form, and when the subscription outgrows the verified value of the work it replaces.
- Managed servicefails when access cannot be revoked, when the operator decides VAT, product-safety or privacy facts that belong to the merchant, and when subcontractors and dependencies stay invisible in the contract.
Keep the manual route if the catalogue is stable, the cycle is reliable and its evidence cost is acceptable. Consider a buyer build where unusual mappings matter and maintenance ownership is funded. Investigate hosted software where repeated standard work dominates. Consider managed delivery when judgement and exception handling matter more than automation.
Before approval, run the defined cycle with synthetic or specifically authorised data. Stop if price, safety, privacy, security, accessibility, VAT or export evidence fails. That is a buyer decision, not a market ranking.
Common questions
What unit does the comparison use across all four routes?
Product change, stock update, order, refund and export.
Why does the comparison leave charges blank?
Subscription, implementation, review time and VAT basis.
