"Keyword optimization" has a bit of a bad reputation, and it's earned one — a lot of the advice out there boils down to "sprinkle the job title into your resume five times" or "paste in a wall of skills nobody will read." That version of keyword optimization is worth avoiding. The underlying reason keywords matter at all is worth understanding properly, because it's not about tricking anything.
What a keyword match actually is
As covered in the previous post, most applicant tracking systems work by turning resumes into searchable, indexed data — a structure not unlike the index at the back of a book, mapping which words appear in which candidate's profile. When a recruiter searches for candidates against a role, they're often (explicitly or through the system's ranking logic) searching by the specific terms in the job posting: the tools, the certifications, the type of work, the seniority language.
A resume that describes real experience using different words than the posting doesn't get flagged as wrong — it just doesn't come up in that search. "Ran paid social campaigns" and "managed digital advertising spend" can describe the same job, but only one of them shows up if the posting's search term is "digital advertising."
This is also, practically, borne out in the data: analysis of first-round resume submissions has found that the average resume is missing roughly half of the keywords the job posting is actually looking for — not because the experience is missing, but because it's described in different language than the one being searched.
Hard skills vs. soft skills, and why they behave differently
Keyword matching works most cleanly on hard skills and named tools — things with a fairly fixed vocabulary: a specific software name, a certification, a programming language, a regulatory framework. If a posting says "Salesforce" and your resume says "CRM software," a keyword search for Salesforce specifically may not surface you, even though you clearly know what they mean.
Soft skills are messier, because they don't have one canonical name — "led cross-functional projects," "stakeholder management," and "collaborated across departments" are all describing something similar, but a keyword match is comparing strings, not meaning (though the more advanced systems are increasingly using semantic matching, which narrows this gap somewhat). The safest approach is still to mirror the posting's specific phrasing where your experience genuinely supports it, rather than assuming a system will infer that your version means the same thing.
Where keyword stuffing goes wrong
The instinct to just cram in every plausible keyword — often invisibly, in white text or a giant list at the bottom — misunderstands both halves of the process. The search/ranking step isn't purely keyword-count-based in most modern systems, so stuffing doesn't reliably help there. And more importantly: an actual person still reads the shortlist. A resume that reads like a list of buzzwords with no real narrative is an obvious red flag to a human reviewer, and it can cost you the interview that the keyword match was supposed to earn you in the first place.
The difference between keyword optimization and keyword stuffing is basically: does the sentence still make sense, and is it still true? "Managed a $2M paid media budget across Google Ads and Meta, focused on customer acquisition" is doing real keyword work — it names the platforms, the type of budget, the goal — while still being a normal, readable sentence about something you actually did. A list that reads "SEO, SEM, PPC, paid media, digital marketing, Google Ads, Meta Ads, budget management, ROI, KPIs" with no sentences around it is not.
The practical version
Read the job posting closely and note its specific nouns — the tools, the certifications, the type of deliverables it names. Then check your resume against that list, not to invent anything, but to see where you're describing the same real experience in different words than the posting uses, and adjust the wording to match where it's honestly accurate. Do that for hard skills especially, since those are the most literal keyword matches; be a little more careful and natural about it for soft skills, since forced buzzword insertion reads worse there than almost anywhere else on a resume.
This is the specific, mechanical work Callback automates: it reads the job description, compares it against your actual resume, and rewrites the wording to close that keyword gap — without inventing experience you don't have, and without turning your resume into a list of buzzwords a human would wince at.
Sources: ResumeAdapter — ATS Statistics 2026, Jobscan — 8 Things You Need to Know About Applicant Tracking Systems