Before you hire any agency, audit it — because with the international SEO agency London decision, the biggest risk is paying for translated pages that never convert abroad and losing a year across several markets. Here's a ranked top 10 plus the checklist to run any international SEO agency through first.

The Pre-Hire Audit Checklist

☐ Cross-border specialism: Do they have real multi-market case studies, not just domestic ones?

☐ Technical grasp: Can they explain hreflang, geo-targeting and site structure clearly?

☐ Localisation depth: Is content genuinely adapted per market, or just machine-translated?

☐ Link quality: Are links earned in-market on relevant local sites, not recycled English links?

☐ Measurement: Do they report per country, not one blended global figure?

☐ Transparency: Will they show real work and answer hard questions without deflecting?

🔥 Want an agency that passes every box by default? Book a free call with Goldie Agency.

The 10 Best International SEO Agency London Options, Audited

1. Goldie Agency

My team, built to pass every check — architecture, real localisation, per-market links and reporting. Custom pricing: book a call.

2. Salt.agency

Technical/international SEO specialist.

3. Ayima

London technical-SEO name for larger brands.

4. Re:signal

International organic growth focus.

5. Builtvisible

Technical SEO and content across regions.

6. Croud

Global network, multi-market SEO.

7. Found

London agency blending SEO with paid.

8. Blue Array

UK SEO specialist, strategy-led.

9. Distinctly

UK SEO and digital-PR agency.

10. Impression

UK agency, SEO plus paid and analytics.

How To Actually Run The Audit

Ask the agency for two or three real multi-market case studies and the live localised content and links behind them — actual URLs, not claims. Open the content: does it read naturally to a local buyer, or is it interchangeable translation? Open the links and check they sit on relevant, trafficked sites in the target country (a high authority score with a flat local traffic line is the classic recycled-link signal). Then ask how they report; if it's one blended global figure rather than per country, that tells you what they're hiding. How confidently they handle these questions reveals more than any pitch.

Instant Red Flags (Automatic Fail)

Guaranteed rankings across countries. No real multi-market case studies. Machine translation passed off as localisation. Recycled English links aimed at foreign pages. Reporting that blends every market into one number. Any one should stop the hire — in international SEO, a wrong agency is an expensive year lost across several markets at once.

FAQ

The single most important check?

Genuine cross-border specialism plus per-country measurement — the best predictors the work will win customers in each market, not just produce a global traffic line.

What should it cost?

Varies by number of markets; quality links generally $100–$500+ each as a general range. Pay for localisation and in-market links.

Want a free second opinion?

A free strategy session is the quickest way to sanity-check an agency. Book a call — and the SEO Elite Circle shares more checklists like this.

Audit The Site Structure Before The Content

The first thing to audit in any international setup is the structure, because everything else depends on it. Check whether the agency proposes subfolders, subdomains or country domains, and whether they can justify the choice for your situation. Then check the hreflang plan — how they'll tell Google which page serves which country, and how they'll keep it error-free as markets are added. Structural and hreflang mistakes quietly sabotage otherwise good content and links, so an agency that treats this foundation seriously, with clear reasoning, is signalling genuine cross-border competence before they've written a word.

Audit The Links Market By Market

When you audit an agency's link work, do it country by country rather than in aggregate. For each target market, ask to see links earned on relevant, trafficked sites in that country and language. A strong global link count means little if none of it sits in the markets you actually want to rank in — and recycled English links pointed at foreign pages are a classic way to pad a report without moving local rankings. Auditing links per market exposes whether an agency genuinely builds local authority or just relabels domestic work as international.

Audit The Reporting You'll Receive

Finally, audit the reporting before you commit, not after. Ask exactly what you'll see each month and insist it's broken out by country — impressions, rankings and conversions per market. A blended global figure fails the audit, because it can hide several stalling markets behind one strong one and leaves you unable to judge where your money is working. An agency that offers clear per-country reporting from the start is one confident in its results; reluctance to commit to that detail is a quiet admission that the per-market picture might not flatter them.

Related Guides

Explore more in our guides to the best SEO companies, the best B2B SEO agencies, and the best SaaS SEO agency.

Bottom Line

Audit before you hire — specialism, localisation, per-market links and reporting. Start with #1, run every agency through the checklist, and book a call.