The right technical SEO agency should prove they actually work in code and server environments, not just run Screaming Frog reports. Ask to see their GitHub contributions, whether they've built custom crawlers or scripts, and how they handle log file analysis. Agencies that only deliver PDF reports without implementation support rarely move the needle. Request a sample technical audit from a similar site in your industry. Strong agencies will show you exactly how they prioritize issues by impact, not just flag everything their tools detect. They should explain the difference between a critical render-blocking resource and a minor schema warning, and why one matters more than the other for your rankings. If they can't distinguish between a 3-point and a 30-point fix, keep looking. Check whether they manage their own properties. At Ottawa SEO, we run 500+ domains specifically because managing a portfolio forces you to solve real technical problems at scale. Agencies that only touch client sites often lack the experimentation needed to understand what actually works versus what sounds good in theory. Ask how many sites they own and operate themselves. Pricing models reveal a lot. Avoid agencies charging $200/month claiming they'll fix everything. Legitimate technical SEO for a mid-sized site runs $3,000-$8,000 for the initial audit and priority fixes, then $1,500-$4,000 monthly for ongoing monitoring and optimization. Agencies working cheaper either offshore the work completely or only handle surface-level issues. Finally, verify they understand your specific platform. WordPress technical SEO differs dramatically from Shopify, React, or custom PHP builds. An agency experienced in your CMS will spot platform-specific issues faster and know which plugins or configurations cause problems. Ask for references from sites on your exact platform, and check whether those sites actually rank for competitive terms. Any agency can claim expertise, but rankings and Core Web Vitals scores don't lie.