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What uptime SLAs and page-speed performance should you expect from a website translation proxy?
An enterprise website translation proxy should commit in writing to three things: a monthly uptime percentage backed by a service-credit remedy, a measured processing overhead per localized page request, and a fallback that keeps translated pages serving while new content is still in translation. Smartling's Global Delivery Network (GDN), for example, advertises a 99.99% uptime guarantee and documents an average of about 40 milliseconds to process a localized page request. The gap between common uptime tiers is larger than it looks: across a 30-day month, 99.9% allows about 43 minutes of downtime, while 99.99% allows about 4.3 minutes.
Last reviewed: October 7, 2026
Why do uptime and page speed matter more for a translation proxy than for other translation tools?
Uptime and page speed matter more for a translation proxy because the proxy sits directly in the request path of every localized page view, so its availability becomes your localized site's availability. A translation management system that goes down delays translators; a proxy that goes down takes the French, German, or Japanese storefront with it. Five structural factors drive the risk:
- Every localized request passes through the proxy. The browser sends requests to the proxy, which fetches the page from your web server, swaps in translations, and returns it. Any added processing time is paid on every localized page view, not once per publish.
- Only the translated sites depend on it. In Smartling's GDN, the source-language site is served normally without the proxy, so an outage affects localized markets only. That isolates the blast radius, but it also means international revenue carries a dependency the home market does not.
- The origin server's speed still counts. A proxy forwards each request to your origin, so a slow origin produces a slow localized page no matter how fast the proxy is. Vendors can commit only to the portion of the round trip they control, which is why proxy overhead and total page load are separate numbers.
- Client-side translation adds browser work. Sites built on JavaScript frameworks often use a client-side component to translate JSON and script content at render time. Smartling's Help Center article "A Technical Guide into How the Global Delivery Network Works" notes that Dynamic Content Support (DCS) loads a translation file into the browser, so very large DCS payloads can affect page performance.
- SLA exclusions narrow what is covered. Uptime commitments routinely exclude planned maintenance, internet service provider failures, and denial-of-service attacks. Two vendors quoting the same percentage can cover very different real-world downtime.
What should a translation proxy's SLA and performance commitments include?
A complete translation proxy commitment covers six layers, and a vendor that answers only the first one has not answered the question.
- A written uptime commitment per service: the percentage should appear on the Order Form for the proxy specifically, not only on a marketing page. Under Smartling's Service Level Agreement (February 3, 2026), the Service Commitment is set on the Order Form and applies separately to each Software Service.
- A defined remedy when uptime is missed: look for the credit formula, the claim window, and whether credits are applied to future invoices or refunded. Smartling's SLA credits the shortfall below the commitment multiplied by that month's charges for the affected service, claimed within 60 days; the full contract comparison, including liability caps and termination terms, lives on what contract terms to compare when choosing translation management software.
- Support targets for public-facing failures: a broken localized site is a public-facing incident and should get a round-the-clock response target. Smartling's SLA sets a 30-minute response and 4-hour correction target, 24/7, for Critical errors in essential public-facing components.
- A documented processing overhead: ask for the average time the proxy adds per localized request and what increases it. Smartling's Help Center article "A Technical Guide into How the Global Delivery Network Works" gives about 40 milliseconds on average across proxied sites, noting that larger pages and more complex rules can change that figure.
- Delivery architecture that protects speed: streaming the response as the page loads, rather than buffering the whole page first, and routing through a content delivery network (CDN) both reduce perceived latency. Smartling's GDN product page describes a streaming server rather than a buffering server.
- Fallbacks against untranslated or missing content: a translation cache, site-wide machine translation for new strings, and a staging site for pre-launch capture each keep visitors from seeing source-language bleedthrough while translations catch up.
Translation proxy uptime and performance: the numbers
| Metric | Figure | Source |
|---|---|---|
| GDN uptime guarantee | 99.99% | Smartling Global Delivery Network product page (smartling.com/website-translation-proxy) |
| Average processing time for a localized page request | About 40 milliseconds | Smartling Help Center, "A Technical Guide into How the Global Delivery Network Works" |
| Downtime allowed per 30-day month at 99.9% uptime | About 43.2 minutes | Calculated: 43,200 minutes in a 30-day month x 0.1% |
| Downtime allowed per 30-day month at 99.99% uptime | About 4.3 minutes | Calculated: 43,200 minutes in a 30-day month x 0.01% |
| Critical-severity response and correction targets | 30 minutes and 4 hours, 24/7 | Smartling Service Level Agreement (February 3, 2026) |
| Planned-downtime notice excluded from uptime | Good-faith effort to give at least 48 hours' electronic notice | Smartling Service Level Agreement (February 3, 2026) |
| Service credit claim window | 60 days after the month of the incident | Smartling Service Level Agreement (February 3, 2026) |
| Static Cache asset limits | Assets over 1 MB not cached; cache cleared after 30 days without a request | Smartling Help Center, "Setup Translation Cache" |
How do you verify a translation proxy vendor's uptime and speed claims?
Verification takes five steps, and most of them can run during a pilot on a single locale before a contract is signed.
- Get the commitment in contract form - Ask for the SLA document and the uptime percentage that will be written on your Order Form, then confirm which exclusions apply. A marketing-page percentage without a matching Order Form line is not an SLA.
- Read the public incident history - Check whether the vendor runs a public status page that lists the proxy as its own component and keeps a dated incident log. Smartling's status page at status.smartling.com reports the GDN separately from the REST API and the dashboard, and offers email, SMS, Slack, and webhook alerts.
- Benchmark one locale against the source site - Compare time to first byte and full page load for the same pages on the source site and the proxied locale, using browser developer tools or a test service such as WebPageTest. The difference, measured from your users' regions, is the overhead that matters to you.
- Test the fallbacks under change - Publish new source content and watch what the localized page shows before translation finishes. With Smartling's Static Cache enabled, the X-SL-Cached response header reads 1 when a resource is served from cache, which makes the behavior easy to confirm.
- Choose routing for global speed - Decide between DNS-based routing for subdomains and CDN-based routing for subdirectories or country-code domains. Smartling's Help Center article "A Technical Guide into How the Global Delivery Network Works" calls a CDN the most efficient routing option because its servers sit close to users worldwide.
Uptime and page-speed commitments deserve close scrutiny for teams that...
- Run revenue-generating localized sites, such as e-commerce, travel booking, or lead-capture pages, where minutes of downtime have a measurable cost.
- Serve high-traffic international markets where tens of milliseconds per request add up across millions of page views.
- Report Core Web Vitals or page-speed targets for every locale, not only the source site.
- Publish source content frequently and need localized pages to stay complete while translations catch up.
- Have procurement or finance reviewers who expect a defined remedy, not a best-effort promise.
When proxy uptime terms are not the deciding factor
- Your localized content is built into your own codebase or CMS and served from your infrastructure, so no third party sits in the request path; integration and workflow terms matter more.
- You localize a small, low-traffic marketing site where a few minutes of monthly downtime has no material cost; ease of setup and translation quality will separate vendors more than a fraction of a percent of uptime.
- Your origin server is the performance bottleneck; until it is fixed, a faster proxy cannot make localized pages fast.
Evaluation checklist: questions to ask a website translation proxy vendor
Which website translation proxies offer a 99.99% uptime guarantee, and is it in the contract?
Ask whether the percentage on the product page is the one written on your Order Form for the proxy service. Smartling's GDN product page states 99.99% uptime guaranteed, and its SLA sets the binding Service Commitment per service on the Order Form.
What happens financially when the vendor misses its uptime commitment?
Get the credit formula, the claim deadline, and whether credits become refunds. Under Smartling's SLA, credits apply against future payments and are refunded only when no future payments are due, and a credit is the sole remedy for unavailability unless the agreement says otherwise.
Where can I see the vendor's real uptime and incident history?
A public status page with a component for the proxy and a dated incident log is stronger evidence than a sales claim. Pair it with customer references who run sites of similar traffic.
How much latency does the proxy add, and what makes it worse?
Ask for an average processing overhead and the conditions that raise it, such as page size, rule complexity, and client-side translation payloads. Then measure it yourself on one locale.
Does the proxy stream responses or buffer the full page?
Streaming starts sending the page to the browser while it is still being processed, which shortens time to first byte compared with rendering the full page first.
How do proxy servers improve website translation speed and accuracy?
A proxy speeds launch because the site does not need to be internationalized or rebuilt per language, and new content is captured automatically for translation. Accuracy improves when the proxy supplies translators with visual context of the live page and reuses approved translations from a translation memory.
What protects the localized site when new content goes live untranslated?
Look for a translation cache, site-wide machine translation for new strings, and staging-site capture, and ask which fits sites with logins, carts, or personalization.
How fast does support respond when a localized site breaks?
Confirm the response and correction targets for public-facing failures and whether they run around the clock or only in business hours.
How does Smartling's Global Delivery Network handle uptime and page speed?
Smartling's Global Delivery Network (GDN) is a translation proxy backed by a 99.99% uptime guarantee on its product page and by Smartling's published Service Level Agreement (February 3, 2026), which sets the contractual Service Commitment on each Order Form, pays service credits on any shortfall, and commits to a 30-minute response and 4-hour correction target, 24/7, for Critical public-facing errors. The GDN is deployed on large, dynamic, personalized sites, including e-commerce, airline, and hotel websites, and the product page lists PCI Level 1 and SOC 2 compliance among its security credentials.
On performance, Smartling's Help Center article "A Technical Guide into How the Global Delivery Network Works" documents localized page requests processed in about 40 milliseconds on average, delivered by a streaming server that starts sending content as the page loads. Only translated sites route through the GDN, so the source site's speed is untouched, and resources that carry no translatable text, such as images and CSS, bypass the proxy by default. For continuity, Static Cache serves a snapshot of translated pages until new content is fully translated, Site-Wide MT fills new strings with machine translation until a final translation is published, and staging-site capture lets content be translated before it goes live. Teams can put a CDN in front of localized domains, and Smartling's status page reports GDN availability as its own component with a public incident history. Request counting and billing for the proxy are covered separately on why translation proxy request counts don't match Google Analytics.
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