Skip to content
Paul Walsh

API integration · Guide

Best Shipping APIs for UK Ecommerce: DPD, Evri and Royal Mail Compared

By Paul Walsh Updated 7 min read

An e-commerce parcel shipping API lets your shop create a carrier label and tracking number from each order automatically, so nobody types addresses into a carrier portal. For UK online shops the three main options are DPD (next-day with a one-hour window), Evri (low-cost standard delivery) and Royal Mail (letters, large letters and every UK address).

Manual despatch, logging into carrier portals and generating labels one at a time, is slow, error-prone and scales poorly. With an API, orders trigger label creation, tracking numbers write back to the order record, and the daily despatch runs without manual work. Each carrier has different strengths, different pricing models and different integration requirements. This guide covers all three, when each is the right choice, and how to decide whether to integrate one or multiple carriers.

DPD API

DPD is the premium UK parcel carrier, built around its one-hour delivery window. When a DPD parcel is out for delivery, the recipient receives a notification specifying their hour slot. They can redirect to a neighbour, safe place or DPD Pickup shop with a tap. Failed first deliveries — the primary driver of customer service contacts and redelivery costs — are significantly less common with DPD than with other carriers because recipients can act on the notification before the driver arrives.

The DPD API uses account-based authentication — username and password provisioned by your DPD Account Manager. There is no self-serve developer portal; credentials are provided through your business account. DPD also requires a minimum shipment volume for a business account. The API itself is straightforward: a REST call creates the shipment, the label is returned as base64 PDF or ZPL, and a consignment number is returned for tracking.

DPD’s API covers: domestic next-day delivery (DPD Classic) with the one-hour window, timed services (pre-10:30am, pre-12pm), Saturday delivery, DPD Pickup (delivery to a local collection point), two-day service, and international shipping. Service codes are specified in the shipment creation call, and a well-built integration selects the service automatically based on the checkout option chosen by the customer.

Best for: businesses where next-day delivery with a precise window is a customer expectation; businesses where failed first deliveries are generating customer service contacts; B2B shipping where timed delivery is a requirement; higher-value items where delivery experience matters.

Integration complexity: moderate. Account-based authentication, no complex OAuth. No manifest submission required. Label returned directly in shipment creation response.

Evri API

Evri is the UK’s volume parcel carrier — handling millions of parcels per week for ASOS, Next, M&S, Etsy and thousands of UK online retailers. Evri (formerly Hermes UK) merged with DHL’s UK ecommerce business in a deal completed in October 2025. Evri’s proposition is cost-effective standard delivery rather than premium next-day experience. For businesses where 3–5 day delivery is acceptable to customers and postage cost per parcel is a meaningful margin consideration, Evri is typically the most competitive carrier.

Evri’s API uses OAuth 2.0 client credentials authentication — Client ID and Client Secret are exchanged for a Bearer access token. Credentials are provisioned by your Evri Account Manager. A Corporate Business account with minimum volume thresholds is required. Evri also requires test labels to be created and submitted for approval before production access — an additional step unique among the three carriers covered here.

Evri’s distinctive feature is its ParcelShop network and QR code returns. Over 7,000 ParcelShop locations allow label-free returns — customers drop a parcel at a participating convenience store and scan a QR code. For high-return-rate product categories (clothing, footwear), removing the print-at-home label requirement significantly increases completed return rates.

Best for: businesses already using Evri as their primary carrier; standard 3–5 day delivery where cost-effectiveness matters; businesses wanting QR code returns for a label-free returns experience; high-volume operations where per-parcel cost is the primary optimisation.

Integration complexity: moderate. OAuth 2.0 authentication with token caching. Parcel value is mandatory (required for insurance). Test label approval adds time to go-live.

Royal Mail API

Royal Mail is the UK’s universal postal service — delivering to every UK address including remote areas, Scottish Highlands, Northern Ireland and islands where other carriers have limited coverage or significant surcharges. Royal Mail is also the only carrier that handles letter and large letter format items economically: a product that fits a large letter (up to 353mm x 250mm x 25mm, under 750g) ships at significantly lower cost than a small parcel.

Royal Mail has multiple API products at different volume thresholds. Click & Drop is available for businesses up to around 1,000 parcels per day and uses a straightforward API key for authentication. Pro Shipping is the higher-volume product using OAuth 2.0, and adds manifest submission at end of day — an additional step not required by DPD or Evri. Royal Mail’s developer portal allows direct API access application, making it the most accessible of the three carriers for getting started.

Tracked 24 (next-day aim) and Tracked 48 (two-day aim) are the core tracked parcel services, covering 1st and 2nd class equivalent speeds. Special Delivery Guaranteed offers a next-day by 1pm guarantee with compensation for late delivery — appropriate for high-value items. Large letter format provides the biggest cost saving: items that fit within the large letter dimensions ship at a fraction of the cost of a small parcel.

Best for: businesses with a mix of letter-format and parcel-format products where format-based routing saves meaningful postage cost; remote UK addresses where other carriers have surcharges; Special Delivery for high-value items requiring guaranteed delivery.

Integration complexity: moderate to higher. Multiple API products to choose from. Pro Shipping requires manifest submission. Click & Drop is simpler but volume-limited.

How the APIs compare

Authentication: DPD uses account credentials (simplest). Royal Mail Click & Drop uses an API key (simple). Evri and Royal Mail Pro Shipping use OAuth 2.0 (more involved). All store credentials server-side.

Self-serve access: Royal Mail has a developer portal where you can apply directly. DPD and Evri both require credentials via an Account Manager — no self-serve option.

Minimum volumes: DPD and Evri both have minimum volume thresholds for business accounts. Royal Mail Click & Drop is accessible at lower volumes with an Online Business Account.

Test label approval: Evri requires test label submission and approval. DPD and Royal Mail do not.

Label formats: all three return labels as base64 PDF (desktop printing) or ZPL (thermal printers). A custom integration can route ZPL labels directly to a thermal print queue without any manual steps.

Tracking: all three provide tracking APIs returning event data by consignment or tracking number. DPD provides the richest tracking experience for end customers, including the one-hour delivery window data.

Build costs

Integration costs for all three carriers are similar at each tier. Standard (shipment creation + label generation + tracking write-back): from £995. Platform integration (standard plus tracking notifications, returns labels, OMS integration): from £1,595. Multi-carrier (two carriers from the same integration layer with automatic selection): from £2,295.

The multi-carrier tier is the highest-value option for ecommerce businesses with mixed shipping requirements. A single integration that selects DPD for next-day, Evri for standard, and Royal Mail for lightweight and remote-address items optimises postage cost and delivery experience simultaneously — and typically recovers the additional build cost in postage savings within a few months.

Which carrier to integrate first

If you’re starting from scratch and currently shipping with one carrier, integrate that carrier first. The immediate time saving from automating your existing workflow is the fastest return on the build cost, and it gives you a working integration to extend rather than building multi-carrier from the outset.

If you’re evaluating carriers alongside evaluating integration, the decision framework is: use DPD if delivery experience is a differentiator; use Evri if postage cost and volume are the priority; use Royal Mail if you have a mix of letter-format products or ship regularly to remote UK addresses. Use two or three if your product range or customer geography makes a single carrier a compromise.

For DPD integration, see the DPD API integration service. For Evri, see the Evri API integration service. For Royal Mail, see the Royal Mail API integration service. For DPD vs Royal Mail specifically, see DPD API vs Royal Mail API. For Evri vs DPD, see Evri API vs DPD API. On OpenCart, OpenCart fixes and support covers connecting your store to these carriers.

If you need help integrating DPD, Evri, Royal Mail or other shipping APIs into your ecommerce store, I can help. I build custom API integrations for UK ecommerce businesses. See API integration pricing or get in touch.

About Paul Walsh

Developer based in Blackburn with 25+ years in electronics and tech. I've run online businesses of my own, and now build and fix websites for small businesses across the UK.

Related guides