diff --git a/app/components/button-with-dialog.hbs b/app/components/button-with-dialog.hbs
new file mode 100644
index 00000000000..2c7220fd7da
--- /dev/null
+++ b/app/components/button-with-dialog.hbs
@@ -0,0 +1,19 @@
+<button
+  type="button"
+  ...attributes
+  {{on "click" (fn this.toggleDialog true)}}
+>
+  {{ @text }}
+</button>
+
+<div
+  local-class="dialog {{ if this.isOpen 'open' }}"
+  role="dialog"
+  aria-label="dialog"
+>
+  {{#if this.isOpen}}
+    <div local-class="dialog__content" data-test-dialog-content>
+      {{yield this.toggleDialog this.isOpen}}
+    </div>
+  {{/if}}
+</div>
\ No newline at end of file
diff --git a/app/components/button-with-dialog.js b/app/components/button-with-dialog.js
new file mode 100644
index 00000000000..9d48244cd34
--- /dev/null
+++ b/app/components/button-with-dialog.js
@@ -0,0 +1,11 @@
+import { action } from '@ember/object';
+import Component from '@glimmer/component';
+import { tracked } from '@glimmer/tracking';
+
+export default class ButtonWithConfirmationDialog extends Component {
+  @tracked isOpen = false;
+
+  @action toggleDialog(state) {
+    this.isOpen = state === undefined ? !this.isOpen : !!state;
+  }
+}
diff --git a/app/components/button-with-dialog.module.css b/app/components/button-with-dialog.module.css
new file mode 100644
index 00000000000..b896dbbfc9f
--- /dev/null
+++ b/app/components/button-with-dialog.module.css
@@ -0,0 +1,24 @@
+.dialog {
+  inset: 0px;
+  overflow-y: auto;
+  display: flex;
+  justify-content: center;
+  z-index: 20;
+  transition: all var(--transition-fast) ease-in;
+  opacity: 0;
+
+  &.open {
+    position: fixed;
+    opacity: 1;
+  }
+}
+
+.dialog__content {
+  --shadow: 0 25px 50px light-dark(hsla(51, 50%, 44%, 0.35), #232321);
+
+  height: min-content;
+  border-radius: var(--space-3xs);
+  box-shadow: var(--shadow);
+  outline: 1px solid var(--gray-border);
+  margin-top: 12.5vh;
+}
diff --git a/app/components/crate-report-form.hbs b/app/components/crate-report-form.hbs
new file mode 100644
index 00000000000..73fd5ec94d2
--- /dev/null
+++ b/app/components/crate-report-form.hbs
@@ -0,0 +1,66 @@
+<form local-class="report-form" {{on "submit" (prevent-default this.submit)}}>
+  <h3>Report Crate "{{@crate}}"</h3>
+
+  <fieldset local-class="form-group" data-test-reasons-group>
+    <div local-class="form-group-name">Reasons</div>
+    <ul role="list" local-class="reasons-list {{if this.reasonsInvalid "invalid"}}">
+      {{#each this.reasons as |option|}}
+        <li>
+          <label data-test-reason={{ option.reason }}>
+            <Input
+              @type="checkbox"
+              @checked={{this.isReasonSelected option.reason}}
+              {{on "change" (fn this.toggleReason option.reason)}}
+            />
+            {{option.description}}
+          </label>
+        </li>
+      {{/each}}
+    </ul>
+    {{#if this.reasonsInvalid}}
+      <div local-class="form-group-error" data-test-error>
+        Please choose reasons to report.
+      </div>
+    {{/if}}
+  </fieldset>
+
+  <fieldset local-class="form-group" data-test-detail-group>
+    {{#let (unique-id) as |id|}}
+      <label for={{id}} local-class="form-group-name">Detail</label>
+      <textarea
+        id={{id}}
+        local-class="detail {{if this.detailInvalid "invalid"}}"
+        aria-required={{if this.detailInvalid "true" "false" }}
+        aria-invalid={{if this.detailInvalid "true" "false"}}
+        rows="5"
+        data-test-detail
+        {{on "change" this.updateDetail}}
+        {{on "input" this.resetDetailValidation}}
+      />
+      {{#if this.detailInvalid}}
+        <div local-class="form-group-error" data-test-error>
+          Please provide some detail.
+        </div>
+      {{/if}}
+    {{/let}}
+  </fieldset>
+
+  <div local-class="buttons">
+    <button
+      type="button"
+      local-class="cancel-button"
+      data-test-cancel
+      {{on "click" this.cancel}}
+    >
+      Cancel
+    </button>
+
+    <button
+      type="submit"
+      local-class="report-button"
+      data-test-report
+    >
+      Report
+    </button>
+  </div>
+</form>
\ No newline at end of file
diff --git a/app/components/crate-report-form.js b/app/components/crate-report-form.js
new file mode 100644
index 00000000000..06acc9076a0
--- /dev/null
+++ b/app/components/crate-report-form.js
@@ -0,0 +1,105 @@
+import { action } from '@ember/object';
+import Component from '@glimmer/component';
+import { tracked } from '@glimmer/tracking';
+
+export default class CrateReportForm extends Component {
+  @tracked selectedReasons = [];
+  @tracked detail = '';
+  @tracked reasonsInvalid;
+  @tracked detailInvalid;
+
+  reasons = [
+    {
+      reason: 'spam',
+      description: 'it contains spam',
+    },
+    {
+      reason: 'name-squatting',
+      description: 'it is name-squatting (reserving a crate name without content)',
+    },
+    {
+      reason: 'abuse',
+      description: 'it is abusive or otherwise harmful',
+    },
+    {
+      reason: 'security',
+      description: 'it contains a vulnerability (please try to contact the crate author first)',
+    },
+    {
+      reason: 'other',
+      description: 'it is violating the usage policy in some other way (please specify below)',
+    },
+  ];
+
+  constructor() {
+    super(...arguments);
+    this.reset();
+  }
+
+  reset() {
+    this.reasonsInvalid = false;
+    this.detailInvalid = false;
+  }
+
+  validate() {
+    this.reasonsInvalid = this.selectedReasons.length === 0;
+    this.detailInvalid = this.selectedReasons.includes('other') && !this.detail?.trim();
+    return !this.reasonsInvalid && !this.detailInvalid;
+  }
+
+  @action resetDetailValidation() {
+    this.detailInvalid = false;
+  }
+
+  @action isReasonSelected(reason) {
+    return this.selectedReasons.includes(reason);
+  }
+
+  @action toggleReason(reason) {
+    this.selectedReasons = this.selectedReasons.includes(reason)
+      ? this.selectedReasons.filter(it => it !== reason)
+      : [...this.selectedReasons, reason];
+    this.reasonsInvalid = false;
+  }
+
+  @action updateDetail(event) {
+    let { value } = event?.target ?? {};
+    this.detail = value ?? '';
+  }
+
+  @action cancel() {
+    this.args.close?.();
+  }
+
+  @action submit() {
+    if (!this.validate()) {
+      return;
+    }
+
+    let mailto = this.composeMail();
+    window.open(mailto, '_self');
+    this.args.close?.();
+  }
+
+  composeMail() {
+    let name = this.args.crate ?? '';
+    let reasons = this.reasons
+      .map(({ reason, description }) => {
+        let selected = this.isReasonSelected(reason);
+        return `${selected ? '- [x]' : '- [ ]'} ${description}`;
+      })
+      .join('\n');
+    let body = `I'm reporting the https://crates.io/crates/${name} crate because:
+
+${reasons}
+
+Additional details:
+
+${this.detail}
+`;
+    let subject = `The "${name}" crate`;
+    let address = 'help@crates.io';
+    let mailto = `mailto:${address}?subject=${encodeURIComponent(subject)}&body=${encodeURIComponent(body)}`;
+    return mailto;
+  }
+}
diff --git a/app/components/crate-report-form.module.css b/app/components/crate-report-form.module.css
new file mode 100644
index 00000000000..429767e1155
--- /dev/null
+++ b/app/components/crate-report-form.module.css
@@ -0,0 +1,69 @@
+.report-form {
+  background-color: var(--main-bg);
+  padding: 0.5rem 1rem;
+}
+
+.form-group {
+  border: none;
+  margin: 0;
+  padding: 0;
+
+  & + & {
+    margin-top: 1rem;
+  }
+}
+
+.form-group-name {
+  composes: form-group-name from '../styles/settings/tokens/new.module.css';
+}
+
+.reasons-list {
+  composes: scopes-list from '../styles/settings/tokens/new.module.css';
+  label {
+    flex-wrap: nowrap;
+  }
+  input {
+    align-self: center;
+  }
+}
+
+.detail {
+  border: 1px solid var(--gray-border);
+  border-radius: var(--space-3xs);
+  resize: vertical;
+  width: 100%;
+
+  &.invalid {
+    background: light-dark(#fff2f2, #170808);
+    border-color: red;
+  }
+}
+
+.form-group-error {
+  composes: form-group-error from '../styles/settings/tokens/new.module.css';
+}
+
+.buttons {
+  composes: buttons from '../styles/settings/tokens/new.module.css';
+  justify-content: end;
+  gap: 2rem;
+}
+
+.button {
+  &:focus {
+    outline: 1px solid var(--bg-color-top-dark);
+    outline-offset: 2px;
+  }
+}
+
+.report-button {
+  composes: button;
+  composes: button small from '../styles/shared/buttons.module.css';
+  border-radius: var(--space-3xs);
+}
+
+.cancel-button {
+  composes: button;
+  composes: tan-button small from '../styles/shared/buttons.module.css';
+  border-radius: var(--space-3xs);
+}
diff --git a/app/components/crate-sidebar.hbs b/app/components/crate-sidebar.hbs
index 1c1d068437b..ff60896827c 100644
--- a/app/components/crate-sidebar.hbs
+++ b/app/components/crate-sidebar.hbs
@@ -130,11 +130,16 @@
       {{/unless}}
     {{/if}}
 
-    <a
-      href="mailto:help@crates.io?subject=The%20%22{{@crate.name}}%22%20crate&body=I'm%20reporting%20the%20https%3A%2F%2Fcrates.io%2Fcrates%2F{{@crate.name}}%20crate%20because%3A%0A%0A-%20%5B%20%5D%20it%20contains%20spam%0A-%20%5B%20%5D%20it%20is%20name-squatting%20(reserving%20a%20crate%20name%20without%20content)%0A-%20%5B%20%5D%20it%20is%20abusive%20or%20otherwise%20harmful%0A-%20%5B%20%5D%20it%20contains%20a%20vulnerability%20(please%20try%20to%20contact%20the%20crate%20author%20first)%0A-%20%5B%20%5D%20it%20is%20violating%20the%20usage%20policy%20in%20some%20other%20way%20(please%20specify%20below)%0A%0AAdditional%20details%3A%0A%0A%3Cplease%20add%20more%20information%20if%20you%20can%3E"
+    <ButtonWithDialog
       local-class="report-button"
+      @text="Report crate"
+      data-test-report-button
+      as |toggleDialog|
     >
-      Report crate
-    </a>
+      <CrateReportForm
+        @crate={{@crate.name}}
+        @close={{fn toggleDialog false}}
+      />
+    </ButtonWithDialog>
   </div>
 </section>
\ No newline at end of file
diff --git a/e2e/acceptance/crate-report-dialog.spec.ts b/e2e/acceptance/crate-report-dialog.spec.ts
new file mode 100644
index 00000000000..734faf9bf49
--- /dev/null
+++ b/e2e/acceptance/crate-report-dialog.spec.ts
@@ -0,0 +1,85 @@
+import { test, expect } from '@/e2e/helper';
+
+test.describe('Acceptance | crate report dialog', { tag: '@acceptance' }, () => {
+  test.beforeEach(async ({ mirage }) => {
+    await mirage.addHook(server => {
+      let crate = server.create('crate', { name: 'nanomsg' });
+      server.create('version', { crate, num: '0.6.0' });
+    });
+  });
+
+  test('display a report form in dialog', async ({ page, percy, a11y }) => {
+    await page.goto('/crates/nanomsg');
+    await page.click('[data-test-report-button]');
+
+    const dialogContent = page.locator('[data-test-dialog-content]');
+    await expect(dialogContent.locator('[data-test-reasons-group]')).toBeVisible();
+    await expect(dialogContent.locator('[data-test-detail-group]')).toBeVisible();
+    await expect(dialogContent.locator('[data-test-cancel]')).toHaveText('Cancel');
+    await expect(dialogContent.locator('[data-test-report]')).toHaveText('Report');
+
+    await percy.snapshot();
+    await a11y.audit();
+  });
+
+  test('empty reasons selected shows an error', async ({ page }) => {
+    await page.goto('/crates/nanomsg/');
+    await page.click('[data-test-report-button]');
+
+    const dialogContent = page.locator('[data-test-dialog-content]');
+    await dialogContent.locator('[data-test-report]').click();
+    await expect(dialogContent.locator('[data-test-reasons-group] [data-test-error]')).toBeVisible();
+    await expect(dialogContent.locator('[data-test-detail-group] [data-test-error]')).toHaveCount(0);
+  });
+
+  test('other reason selected without given detail shows an error', async ({ page }) => {
+    await page.goto('/crates/nanomsg/');
+    await page.click('[data-test-report-button]');
+
+    const dialogContent = page.locator('[data-test-dialog-content]');
+    await dialogContent.locator('[data-test-reason="spam"]').click();
+    await dialogContent.locator('[data-test-reason="other"]').click();
+    await dialogContent.locator('[data-test-report]').click();
+    await expect(dialogContent.locator('[data-test-reasons-group] [data-test-error]')).toHaveCount(0);
+    await expect(dialogContent.locator('[data-test-detail-group] [data-test-error]')).toBeVisible();
+  });
+
+  test('valid report form should compose a mail and open', async ({ page }) => {
+    // mock `window.open()`
+    await page.addInitScript(() => {
+      globalThis.open = (url, target, features) => {
+        globalThis.openKwargs = { url, target, features };
+        return { document: { write() {}, close() {} }, close() {} } as ReturnType<(typeof globalThis)['open']>;
+      };
+    });
+
+    await page.goto('/crates/nanomsg/');
+    await page.click('[data-test-report-button]');
+
+    const dialogContent = page.locator('[data-test-dialog-content]');
+    await dialogContent.locator('[data-test-reason="spam"]').click();
+    await dialogContent.locator('[data-test-reason="other"]').click();
+    await dialogContent.locator('[data-test-detail]').fill('test detail');
+    await dialogContent.locator('[data-test-report]').click();
+
+    let body = `I'm reporting the https://crates.io/crates/nanomsg crate because:
+
+- [x] it contains spam
+- [ ] it is name-squatting (reserving a crate name without content)
+- [ ] it is abusive or otherwise harmful
+- [ ] it contains a vulnerability (please try to contact the crate author first)
+- [x] it is violating the usage policy in some other way (please specify below)
+
+Additional details:
+
+test detail
+`;
+    let subject = `The "nanomsg" crate`;
+    let address = 'help@crates.io';
+    let mailto = `mailto:${address}?subject=${encodeURIComponent(subject)}&body=${encodeURIComponent(body)}`;
+    // wait for `window.open()` to be called
+    await page.waitForFunction(expect => globalThis.openKwargs.url === expect, mailto);
+    await page.waitForFunction(expect => globalThis.openKwargs.target === expect, '_self');
+    await expect(dialogContent).not.toBeVisible();
+  });
+});
diff --git a/tests/acceptance/crate-report-dialog.js b/tests/acceptance/crate-report-dialog.js
new file mode 100644
index 00000000000..721d3d7f7f9
--- /dev/null
+++ b/tests/acceptance/crate-report-dialog.js
@@ -0,0 +1,97 @@
+import { click, fillIn } from '@ember/test-helpers';
+import { module, test } from 'qunit';
+
+import percySnapshot from '@percy/ember';
+import a11yAudit from 'ember-a11y-testing/test-support/audit';
+import window from 'ember-window-mock';
+import { setupWindowMock } from 'ember-window-mock/test-support';
+
+import { setupApplicationTest } from 'crates-io/tests/helpers';
+
+import axeConfig from '../axe-config';
+import { visit } from '../helpers/visit-ignoring-abort';
+
+module('Acceptance | create report dialog', function (hooks) {
+  setupApplicationTest(hooks);
+  setupWindowMock(hooks);
+
+  function prepare(context) {
+    let server = context.server;
+    let crate = server.create('crate', { name: 'nanomsg', newest_version: '0.6.0' });
+    server.create('version', { crate, num: '0.6.0' });
+  }
+
+  test('display a report form in dialog', async function (assert) {
+    prepare(this);
+
+    await visit('/crates/nanomsg');
+    await click('[data-test-report-button]');
+
+    assert.dom('[data-test-dialog-content] [data-test-reasons-group]').exists();
+    assert.dom('[data-test-dialog-content] [data-test-detail-group]').exists();
+    assert.dom('[data-test-dialog-content] [data-test-cancel]').hasText('Cancel');
+    assert.dom('[data-test-dialog-content] [data-test-report]').hasText('Report');
+
+    await percySnapshot(assert);
+    await a11yAudit(axeConfig);
+  });
+
+  test('empty reasons selected shows an error', async function (assert) {
+    prepare(this);
+
+    await visit('/crates/nanomsg');
+    await click('[data-test-report-button]');
+
+    await fillIn('[data-test-name]', 'test detail');
+    await click('[data-test-dialog-content] [data-test-report]');
+    assert.dom('[data-test-dialog-content] [data-test-reasons-group] [data-test-error]').exists();
+    assert.dom('[data-test-dialog-content] [data-test-detail-group] [data-test-error]').doesNotExist();
+  });
+
+  test('other reason selected without given detail shows an error', async function (assert) {
+    prepare(this);
+
+    await visit('/crates/nanomsg');
+    await click('[data-test-report-button]');
+
+    await click('[data-test-dialog-content] [data-test-reason="spam"]');
+    await click('[data-test-dialog-content] [data-test-reason="other"]');
+    await click('[data-test-dialog-content] [data-test-report]');
+    assert.dom('[data-test-dialog-content] [data-test-reasons-group] [data-test-error]').doesNotExist();
+    assert.dom('[data-test-dialog-content] [data-test-detail-group] [data-test-error]').exists();
+  });
+
+  test('valid report form should compose a mail and open', async function (assert) {
+    prepare(this);
+    let fakeWindow = { document: { write() {}, close() {} }, close() {} };
+    window.open = (url, target) => {
+      let body = `I'm reporting the https://crates.io/crates/nanomsg crate because:
+
+- [x] it contains spam
+- [ ] it is name-squatting (reserving a crate name without content)
+- [ ] it is abusive or otherwise harmful
+- [ ] it contains a vulnerability (please try to contact the crate author first)
+- [x] it is violating the usage policy in some other way (please specify below)
+
+Additional details:
+
+test detail
+`;
+      let subject = `The "nanomsg" crate`;
+      let address = 'help@crates.io';
+      let mailto = `mailto:${address}?subject=${encodeURIComponent(subject)}&body=${encodeURIComponent(body)}`;
+      assert.strictEqual(url, mailto);
+      assert.strictEqual(target, '_self');
+      return fakeWindow;
+    };
+
+    await visit('/crates/nanomsg');
+    await click('[data-test-report-button]');
+
+    await click('[data-test-dialog-content] [data-test-reason="spam"]');
+    await click('[data-test-dialog-content] [data-test-reason="other"]');
+    await fillIn('[data-test-name]', 'test detail');
+    await click('[data-test-dialog-content] [data-test-report]');
+    assert.dom('[data-test-dialog-content]').doesNotExist();
+  });
+});