Best AI for cover letters
The hard cover letter is the one for a job you only partly qualify for - you want it to sell you without saying anything the CV cannot back, and to handle the gap year with some dignity. We gave nine assistants a fictional CV that misses four of six requirements, a brief that forbids stretching, and read every line.
People also look for this as cover letter generator, cover letter writer, write my cover letter or job application letter.
Our picks, side by side
Rated for this task · 0–3
Measured
Quality
Effort
Cost
Free tier
From
Why
★ Best overall
ChatGPT
$8/mo · free tier: usableMeasured5 of 5 honesty · numbers exact · 197 words · all 4 gaps named · ~30 s
Quality
Effort
Cost
Free tierUnlimited text chat on the default model, with limits on uploads, images, voice and deep research
From$8/mo
Why
Every number right, the break in one honest sentence, and one paragraph that names all four things the CV lacks - HubSpot, a managed team, five years, a degree - so the reader hears it from you, not from the CV. Under 200 words, a close that asks for a conversation and nothing else, and it arrives as an email card with a send button. It offers a "more confident and persuasive" version afterwards; you do not need it.
Best if you would rather not list what you lack
Claude
$20/mo · free tier: usableMeasured5 of 5 honesty · numbers exact · 206 words · gaps left out, listed after · ~40 s
Quality
Effort
Cost
Free tierChat with web search and file uploads, with a usage cap per five-hour session
From$20/mo
Why
The most careful letter of the nine. It says what the CV says - the numbers exact, the diploma as a diploma, freelancers briefed - and does not mention HubSpot, a team or five years at all, in either direction. That is the other honest way to write this, and the brief allowed it. Then it tells you, after the letter, exactly which claims it left out and why. Adds the C1 English the job asked for, which the CV has.
Best if you want the gaps said plainly
DeepSeek
Free · free tier: usableMeasured5 of 5 honesty · numbers exact · 212 words · all 4 gaps named, one word too generous · ~20 s
Quality
Effort
Cost
Free tierThe full chat app with web search and file uploads; there is no paid consumer tier
FromFree
Why
"I should be honest about where I don't yet match your requirements" - and then all four, in plain words: four years not five, freelancers not an in-house team, Mailchimp not HubSpot, a two-year diploma. The break gets "I'll be straightforward". One phrase leans the wrong way, "My HubSpot experience is also limited", where there is none, and the same sentence puts it right. Twenty seconds, no sign-off word, just the name.
Evidence
5 of 5 honesty checks; every number exact; 197 words in the body; all 4 gaps named; addressed, signed, close asks for a conversation only; ~30 s.
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All 9 tools we tested
Rated for this task only · 0–3| Tool | Quality | Effort | Cost | Free tier | Measured | From |
|---|---|---|---|---|---|---|
| ChatGPTFree: Unlimited text chat on the default model, with limits on uploads, images, voice and deep research | 5 of 5 honesty · numbers exact · 197 words · all 4 gaps named · ~30 s | $8/mo | ||||
| ClaudeFree: Chat with web search and file uploads, with a usage cap per five-hour session | 5 of 5 honesty · numbers exact · 206 words · gaps left out, listed after · ~40 s | $20/mo | ||||
| GeminiFree: The default model with usage limits, plus Gemini inside Maps, Gmail and Docs on a free Google account | 5 of 5 honesty · numbers exact · 185 words · gaps left out · ~90 s | $19.99/mo | ||||
| PerplexityFree: Unlimited basic searches with a weekly cap on Pro-model searches | refused - would not write for a CV in a name not the account's · ~15 s | $20/mo | ||||
| Microsoft CopilotFree: The Copilot app on web, Windows and mobile with usage limits | 5 of 5 honesty · one number used · 198 words · 3 gaps named · ~30 s | $19.99/mo | ||||
| DeepSeekFree: The full chat app with web search and file uploads; there is no paid consumer tier | 5 of 5 honesty · numbers exact · 212 words · all 4 gaps named, one word too generous · ~20 s | Free | ||||
| GrokFree: Chat with web and X search within generous limits, no card required | 5 of 5 honesty · numbers exact · 178 words · gaps left out · 21 s | $30/mo | ||||
| QwenFree: The full chat app; there is no paid consumer tier | 5 of 5 honesty · numbers exact · 122 words, bare · ~3 min | Free | ||||
| KimiFree: Unlimited basic chat, file upload and web access on the free plan | 5 of 5 honesty · numbers exact · 262 words, over the limit · ~40 s | $19/mo |
How we tested
The same fictional CV and job description as our résumés test, so the two pages can be read together - a marketing coordinator with four years, Mailchimp not HubSpot, freelancers briefed rather than a team managed, a two-year diploma, and a seventeen-month caregiving break, applying for a manager's role that asks for five years, HubSpot, people management and a degree.
One message to ChatGPT, Claude, Gemini, Perplexity, Microsoft Copilot, DeepSeek, Grok, Qwen and Kimi on their free tiers, memory off, in a fresh chat - under 250 words, to a named hiring manager, signed, only what the CV says, every number exact, the break in one honest sentence, and a close that asks for a conversation and nothing more.
A script checked five honesty points - no HubSpot, no degree, no managed team, no five years, the break named - plus every number against the CV, the body word count and the framing. Then we read each letter for what it added and for how it handled the four gaps - named outright, or left out, both of which the brief allowed.
Eight wrote a letter and all eight passed every honesty check with every number exact. ChatGPT and DeepSeek named all four gaps, Copilot three, and Claude, Gemini, Grok and Qwen left them unsaid. Kimi ran to 262 words against the limit of 250. Perplexity refused, saying the CV was not in the account holder's name.
The test was run by, or under the direction of, the one person who runs this site, with AI assistance, and every output and fact-check was reviewed by them. The surrounding text was drafted with AI assistance from our own ratings and evidence, then checked and edited by the same person. If something here is wrong, tell us and we will fix it and say so.
Questions people ask
Which AI writes the best cover letter?
On this test, ChatGPT - every fact right, every gap named in one honest paragraph, under 200 words, and delivered as a send-ready email card. Claude is the pick if you would rather not list what you lack, and tells you afterwards what it left out. DeepSeek says the gaps most plainly. All eight that wrote a letter kept to the CV.
Will it make things up to fit the job?
Not one of the eight did, on a brief that forbade it - no HubSpot, no degree, no managed team, no five years, and every number quoted was exact. The stretch to watch for is a word, not a fact - DeepSeek's "My HubSpot experience is also limited" where there is none, Gemini's "freelance team coordination". Read the sentence about the thing you lack.
How do they handle a career break?
All eight named it in one sentence with the dates and the reason, as asked. Copilot, ChatGPT, DeepSeek and Grok stated it flat; Kimi prefaced it with "Rather than hide it"; DeepSeek with "I'll be straightforward". None hid it and none apologised for it.
Why did Perplexity refuse?
Because it knew the account holder's name and the CV was in another - "using Inês's CV would misrepresent your experience". Our CV is a fixture, so for us that was a refusal to do the job; for someone writing a letter for a friend or a client it will be the same. The other eight took "my CV" at its word.