WPML String Translation is the WPML component that handles everything WPML Core cannot: the strings that do not live in posts and pages – theme texts, plugin labels, widget titles, admin screens, settings options, URL slugs, and texts generated in code. A translated site is only as complete as its strings; a storefront where the product page is translated but “Add to cart,” checkout labels, and category slugs are not, is visibly half-finished. This add-on scans themes and plugins, registers every translatable string, and lets translation managers fill in the gaps – manually, via .po files, or through WPML’s automatic translation. Related reading: our multilingual core layer overview covers the adjacent workflow.
The 5.0 release, shipped in the September 2026 coordinated update across the whole WPML family, is a performance rebuild: indexed string lookups instead of full scans, fault-tolerant queues where one bad file no longer blocks everything behind it, memory-bounded language-file caches, and working taxonomy-slug translation. For large multilingual sites – the ones with thousands of auto-registered frontend strings – those fixes address the exact failure modes that made the Strings screen a timeout generator.
Competitive Features
Complete string coverage. Themes, plugins, admin screens, widgets, options, and slugs – the layer beyond content that makes a site genuinely multilingual.
Indexed string lookups (5.0). The Strings screen loads via indexed queries instead of scanning every string – the difference between a screen and a timeout on large sites.
Fault-tolerant translation queues. Auto-registered frontend strings process through a queue where a single bad file or database write no longer blocks the rest.
Taxonomy and slug translation that works (5.0). Translated slugs now take effect on the front end, and taxonomy labels register under the correct source language.
.po file import. Standard gettext files upload and apply to selected strings – the workflow for professional translation suppliers.
English-variant correctness. Sites whose default language is en-US or en-GB behave consistently instead of hitting string-matching edge cases.
Key Features
- String search – by text and by language name (restored in 5.0), with per-domain and per-context filtering.
- Auto-registration – frontend strings detected and queued automatically as pages render.
- Translation Manager support – non-admin managers change string languages without JavaScript errors (fixed 5.0).
- Custom REST prefix support – WPML respects non-default REST API prefixes (5.0).
- Symlink installs – theme and plugin scanning works through symbolic links (fixed 5.0).
- Memory-bounded caches – language-file caches stay within a safe memory budget.
- Security hardening – included in the 5.0 release line.
Comparison with Competitors
WPML String Translation vs WPML Core
Not a competitor – a required companion. The relationship matters to understand.
| WPML Core | String Translation | |
|---|---|---|
| Scope | Posts, pages, custom types, menus | Theme/plugin strings, slugs, admin |
| Without the other | Site content translated, UI not | Strings translated, no content layer |
| Setup | Standalone | Requires Core |
| Together | The complete multilingual site | – |
No WPML site skips this add-on for long; it is where the last 20% of visible translations live.
WPML String Translation vs Polylang Pro
The broader platform comparison: WPML’s modular stack versus Polylang’s consolidated plugin.
| WPML (+ String Translation) | Polylang Pro | |
|---|---|---|
| Architecture | Core + specialized add-ons | Single plugin with pro modules |
| String handling | Dedicated add-on with queue system | Built-in (limited) |
| Automatic translation | Default in WPML 5.0 | Optional service |
| Ecosystem | Largest integration catalog | Growing |
| Best for | Complex, large multilingual sites | Simpler multilingual needs |
Polylang covers basics inside the plugin; WPML’s dedicated string layer with indexed lookups and queue tolerance is what large sites converge on. See Polylang Pro for the other side.
Recommended Stack: teams avoiding the add-on stack entirely compare with Weglot – the hosted translation service bundles string handling into its infrastructure, a different architecture for the same coverage.
Official Changelog
Version 5.0.2
Release Date: September 22, 2026
- Fixed: fatal error in wp-admin and front end on hosts disabling PHP’s
getmypid(); translation files write correctly again - Changed: download no longer includes .po translation source files
Version 5.0.0
Release Date: September 13, 2026
- Faster Strings screen via indexed lookup; adding a language no longer times out; large auto-registered-string queues no longer hit timeouts
- Fault-tolerant string registration and pending-strings queue; memory-bounded language-file cache
- Fixed: taxonomy slug translation now takes effect on the front end; taxonomy labels registered under the correct source language; consistent behavior on en-US/en-GB default-language sites; string search by language name and text; .po upload and string adding; string-language changes for non-admin Translation Managers; theme/plugin scanning through symbolic links; custom REST API prefix support
- Security: hardening included
Version 3.5.3
Release Date: earlier maintenance release
- Maintenance release from the previous 3.x line, superseded by the 5.0 rewrite
Frequently Asked Questions
Do I need this if WPML Core is installed?
Practically yes – Core translates posts, pages, and custom types, but theme texts, plugin labels, admin screens, widgets, and URL slugs all live in this add-on. A site without it shows translated content wrapped in untranslated interface strings.
What changed in the 5.0 rebuild?
Performance and resilience: indexed string lookups replace full scans, translation queues survive individual bad files, language-file caches stay memory-bounded, and taxonomy slug translation actually works on the front end. For sites with thousands of auto-registered strings, the Strings screen stops timing out.
Can I import professional translations via .po files?
Yes – standard gettext .po files upload and apply to selected strings on the Strings tab (functionality restored in 5.0). This is the standard workflow with translation suppliers and CAT-tool exports.
My host disables getmypid() and the site broke after WPML 5.0 – is there a fix?
Yes – version 5.0.2 fixes exactly that fatal error, and translation files write correctly again. It is the current release and the answer for restricted shared hosting.
Does it handle URL slug translation?
Yes – taxonomy slugs translate and take effect on the front end as of 5.0, which matters for localized SEO where a translated category path is part of the URL strategy.
How does the WPML stack compare to Polylang for a new multilingual site?
Polylang Pro consolidates basics into one plugin and suits simpler needs. WPML’s add-on architecture – dedicated string translation with queue infrastructure, plus the largest integration catalog – is what complex sites with many plugins and large string volumes converge on. See Polylang Pro for the alternative.
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