What is Web EDI? A guide for UK suppliers

A large buyer asks a small business to trade by EDI, and the business has no EDI system and nobody to build one. Web EDI was built for that case. GS1, the global standards body, describes it as a way for "the big companies to integrate their small business partners in the EDI." In the UK, NHS Supply Chain, HMRC and Transport for London each publish how their supplier portals work.

What is web EDI?

EDI, electronic data interchange, is the exchange of business documents such as orders and invoices as structured data between two companies' systems. Web EDI lets a supplier exchange EDI documents through a web browser, with no EDI software or IT team. Through a provider's web EDI portal, the customer's system receives a standard EDI message. Through a customer's own portal, the data goes straight into that customer's system.

GS1's knowledge base puts it this way: "The Web EDI involves the exchange of electronic documents via an internet-enabled Web EDI platform." We found no UK body that publishes a formal definition, so we use GS1's.

In GS1's model, the supplier sees forms and the customer receives EDI. Nothing in between asks the supplier to understand the format.

Three ways a supplier can trade by EDI

Two of the three routes use a browser. The difference is who runs the screen and whose rules it follows.

How does web EDI work?

Two translations happen, one in each direction.

From your customer to you. Your customer's system sends an EDI order, and the portal turns it into a readable form. GS1 describes the step: "The traditional EDI message sent by the large user company is transformed into the HTML form and sent to the Web EDI user."

From you to your customer. You fill in a form, usually an invoice or a despatch note built from the order you received, and translation software takes over: "The software converts it into the relevant EDI standard, e.g. GS1 EANCOM® or GS1 XML and transfers to the big user company."

Your customer's system does not care that you typed into a browser. It checks the message it receives. For UK grocery, GS1 UK's 2016 Perfect Order requirements list the minimum content of a despatch advice, including "SSCCs identifying each logistics unit" and "GTINs to identify each product line", and say: "The format of all ASN messages shall conform to GS1 EDI standards (EANCOM or GS1 XML)."

The SSCC guide covers the pallet codes, and the OTIF guide shows how buyers score deliveries.

Your customer's portal or your provider's portal: what is the difference?

Both turn browser input into data your customer can use. They differ in who runs the screen and whose rules it follows.

A customer's portal is set up by the buyer. The supplier portal guide says: "The portal belongs to your customer, so the rules do too." It puts the contrast in two sentences: "A supplier portal is a screen your customer gives you. EDI is a connection between your system and theirs." Three UK buyers show how these portals work:

• NHS Supply Chain. Its Operational Supplier Requirements, Version 4.1, uploaded in March 2025, say: "All orders are sent to suppliers electronically either via EDI or e-mail." In its supplier portal, a supplier raises the invoice from the order, completes advance shipment notices to book depot deliveries, and handles labels: "Suppliers can either produce labels themselves or print the labels from the supplier portal."
• HMRC. It runs supplier invoicing through SAP Ariba, where the "invoice is automatically pre-populated with the purchase order data." A supplier can register a free account or use its "existing Ariba Network account", and HMRC's guide points suppliers to "HMRC Invoice Rules".
• Transport for London. It issues purchase orders through SAP Business Network, through EDI or by email, and strongly encourages suppliers to register on that network, for free, to receive orders and submit invoices. One benefit it lists is that suppliers "can connect with other buying organisations also using SAP".

NHS Supply Chain's portal serves NHS Supply Chain. HMRC and Transport for London use SAP's network, which other buyers use too, so one supplier account can serve more than one customer there. SAP says the standard account is free, but the supplier portal guide notes that it becomes chargeable once a supplier passes document and value thresholds with one buyer. Each buyer still sets what it asks for. Sell to five customers that each run a separate portal, and you have five log-ins and five sets of rules.

A provider's web EDI portal is run by an EDI provider. One log-in reaches each trading partner the provider connects you to, and the provider produces the format each one asks for. The what is EDI guide describes this route as "A browser-based service with no integration required, used to view and action documents online".

The two can sit side by side. A buyer that runs its own portal may still ask you to use it, whatever route you use for everyone else.

Web EDI vs integrated EDI: which do you need?

The difference is who moves the data. With web EDI, a person reads each order and keys each invoice. With integrated EDI, your own system does it.

The managed EDI guide puts the result plainly: "Integrated EDI connects your ERP, accounting or warehouse system so orders and invoices flow without rekeying."

You do not have to pick one for good. The what is EDI guide adds: "A single business often uses more than one method at once, for example web EDI for a handful of small trading partners and a direct integration for its largest retail account, all managed through the same provider and the same underlying connection."

Who is web EDI for, and when do suppliers outgrow it?

Web EDI suits a supplier starting its first EDI relationship, with a few trading partners and simple documents. The affordable EDI guide says: "A web portal suits an organisation that needs a connection for one trading partner with simple message types."

We found no published order count or partner count at which web EDI stops working. The signs are practical:

• Keying becomes the job. Volvo Group, a buyer that runs its own web EDI tool, says its messages are "easy to read, although they are handled manually." Every order read and every invoice typed is a person's time.
• Buyers point you to integration. HMRC says connecting an ERP to the Ariba Network "is normally used where there is a high volume of transactions and will be completed at your expense."
• Partners multiply. The deciding on EDI services guide says an organisation with "a large network of trading connections, each with its own message requirements and EDI protocols will benefit from integrated EDI services or middleware EDI".

The affordable EDI guide gives the rule of thumb: "Once order volumes make rekeying a burden, an integrated setup becomes worth considering." So pick a web route that can grow into integration on the same connection. Moving up then changes the method and keeps the connection.

Does web EDI help with eInvoicing and Peppol?

It depends on what the invoice is, and the rules for EDI are not decided yet.

The government's roadmap for eInvoicing, published on 28 October 2026, says: "As announced at Budget 2025, the government will require that VAT invoices are issued as e-invoices from April 2029." It adds that "the UK will adopt Peppol as the core interoperability framework for e-invoicing".

An eInvoice, in the roadmap's sense, is structured data. Formats including PDFs and "HTML invoices on a web page or email and images sent via fax machine do not count as e-invoices". A web EDI portal that sends your customer a structured EDI message is a different thing, though that alone does not settle the 2029 question.

Whether a web EDI invoice will meet the 2029 rules is undecided. On existing EDI, the roadmap states an intention rather than a rule: that "businesses can continue using these arrangements alongside the future UK e-invoicing framework", and that "businesses using them will also need to be capable of exchanging e-invoices through the future framework". It says further guidance follows in Autumn 2027. The UK eInvoicing mandate page tracks what the government has published so far.

Peppol is a framework, not an app you install, and a supplier reaches it through a provider. The Transalis eInvoicing page describes a browser route to it: "With Web eInvoicing you get compliant on the Peppol network through a managed portal, no in-house technical staff and no change to your accounting system."

How Transalis Web EDI works

Transalis is a managed outcomes provider for B2B integration, EDI and eInvoicing. Transalis Web EDI is its browser route, on Transalis OpenEDI™.

The EDI page describes it as "A managed web portal to receive orders, send invoices and manage compliance in a browser. No ERP integration and no software to install, with automated pallet-label (SSCC) printing for retailer compliance built in."

Managed means the format work sits with Transalis: "We handle the complexity of format translation, partner onboarding, compliance monitoring and error resolution, so you get results without running software."

"Many Transalis customers begin with Web EDI for their first retail buyer and scale to Integrated and Enterprise EDI as they grow". As the retail supplier playbook puts it: "You can move to integrated EDI later on the same network."

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