diff --git a/nip99.test.ts b/nip99.test.ts
new file mode 100644
index 0000000..442cd6b
--- /dev/null
+++ b/nip99.test.ts
@@ -0,0 +1,506 @@
+import { describe, expect, test } from 'bun:test'
+
+import { Event } from './core'
+import { ClassifiedListing, DraftClassifiedListing } from './kinds'
+import { ClassifiedListingObject, generateEventTemplate, parseEvent, validateEvent } from './nip99'
+import { finalizeEvent, generateSecretKey } from './pure'
+
+describe('validateEvent', () => {
+  test('should return true for a valid classified listing event', () => {
+    const sk = generateSecretKey()
+    const event: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: ClassifiedListing,
+        content:
+          'Lorem [ipsum][nostr:nevent1qqst8cujky046negxgwwm5ynqwn53t8aqjr6afd8g59nfqwxpdhylpcpzamhxue69uhhyetvv9ujuetcv9khqmr99e3k7mg8arnc9] dolor sit amet. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.\n\nRead more at nostr:naddr1qqzkjurnw4ksz9thwden5te0wfjkccte9ehx7um5wghx7un8qgs2d90kkcq3nk2jry62dyf50k0h36rhpdtd594my40w9pkal876jxgrqsqqqa28pccpzu.',
+        tags: [
+          ['d', 'sample-title'],
+          ['title', 'Sample Title'],
+          ['summary', 'Sample Summary'],
+          ['published_at', '1296962229'],
+          ['location', 'NYC'],
+          ['price', '100', 'USD'],
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['t', 'tag1'],
+          ['t', 'tag2'],
+          ['e', 'value1', 'value2'],
+          ['a', 'value1', 'value2'],
+        ],
+      },
+      sk,
+    )
+
+    expect(validateEvent(event)).toBe(true)
+  })
+
+  test('should return false when the "d" tag is missing', () => {
+    const sk = generateSecretKey()
+    const event: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: ClassifiedListing,
+        content:
+          'Lorem [ipsum][nostr:nevent1qqst8cujky046negxgwwm5ynqwn53t8aqjr6afd8g59nfqwxpdhylpcpzamhxue69uhhyetvv9ujuetcv9khqmr99e3k7mg8arnc9] dolor sit amet. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.\n\nRead more at nostr:naddr1qqzkjurnw4ksz9thwden5te0wfjkccte9ehx7um5wghx7un8qgs2d90kkcq3nk2jry62dyf50k0h36rhpdtd594my40w9pkal876jxgrqsqqqa28pccpzu.',
+        tags: [
+          // Missing 'd' tag
+          ['title', 'Sample Title'],
+          ['summary', 'Sample Summary'],
+          ['published_at', '1296962229'],
+          ['location', 'NYC'],
+          ['price', '100', 'USD'],
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['t', 'tag1'],
+          ['t', 'tag2'],
+          ['e', 'value1', 'value2'],
+          ['a', 'value1', 'value2'],
+        ],
+      },
+      sk,
+    )
+
+    expect(validateEvent(event)).toBe(false)
+  })
+
+  test('should return false when the "title" tag is missing', () => {
+    const sk = generateSecretKey()
+    const event: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: ClassifiedListing,
+        content:
+          'Lorem [ipsum][nostr:nevent1qqst8cujky046negxgwwm5ynqwn53t8aqjr6afd8g59nfqwxpdhylpcpzamhxue69uhhyetvv9ujuetcv9khqmr99e3k7mg8arnc9] dolor sit amet. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.\n\nRead more at nostr:naddr1qqzkjurnw4ksz9thwden5te0wfjkccte9ehx7um5wghx7un8qgs2d90kkcq3nk2jry62dyf50k0h36rhpdtd594my40w9pkal876jxgrqsqqqa28pccpzu.',
+        tags: [
+          ['d', 'sample-title'],
+          // Missing 'title' tag
+          ['summary', 'Sample Summary'],
+          ['published_at', '1296962229'],
+          ['location', 'NYC'],
+          ['price', '100', 'USD'],
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['t', 'tag1'],
+          ['t', 'tag2'],
+          ['e', 'value1', 'value2'],
+          ['a', 'value1', 'value2'],
+        ],
+      },
+      sk,
+    )
+
+    expect(validateEvent(event)).toBe(false)
+  })
+
+  test('should return false when the "summary" tag is missing', () => {
+    const sk = generateSecretKey()
+    const event: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: ClassifiedListing,
+        content:
+          'Lorem [ipsum][nostr:nevent1qqst8cujky046negxgwwm5ynqwn53t8aqjr6afd8g59nfqwxpdhylpcpzamhxue69uhhyetvv9ujuetcv9khqmr99e3k7mg8arnc9] dolor sit amet.\n\nRead more at nostr:naddr1qqzkjurnw4ksz9thwden5te0wfjkccte9ehx7um5wghx7un8qgs2d90kkcq3nk2jry62dyf50k0h36rhpdtd594my40w9pkal876jxgrqsqqqa28pccpzu.',
+        tags: [
+          ['d', 'sample-title'],
+          ['title', 'Sample Title'],
+          // Missing 'summary' tag
+          ['published_at', '1296962229'],
+          ['location', 'NYC'],
+          ['price', '100', 'USD'],
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['t', 'tag1'],
+          ['t', 'tag2'],
+          ['e', 'value1', 'value2'],
+          ['a', 'value1', 'value2'],
+        ],
+      },
+      sk,
+    )
+
+    expect(validateEvent(event)).toBe(false)
+  })
+
+  test('should return false when the "published_at" tag is missing', () => {
+    const sk = generateSecretKey()
+    const event: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: ClassifiedListing,
+        content:
+          'Lorem [ipsum][nostr:nevent1qqst8cujky046negxgwwm5ynqwn53t8aqjr6afd8g59nfqwxpdhylpcpzamhxue69uhhyetvv9ujuetcv9khqmr99e3k7mg8arnc9] dolor sit amet. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.\n\nRead more at nostr:naddr1qqzkjurnw4ksz9thwden5te0wfjkccte9ehx7um5wghx7un8qgs2d90kkcq3nk2jry62dyf50k0h36rhpdtd594my40w9pkal876jxgrqsqqqa28pccpzu.',
+        tags: [
+          ['d', 'sample-title'],
+          ['title', 'Sample Title'],
+          ['summary', 'Sample Summary'],
+          // Missing 'published_at' tag
+          ['location', 'NYC'],
+          ['price', '100', 'USD'],
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['t', 'tag1'],
+          ['t', 'tag2'],
+          ['e', 'value1', 'value2'],
+          ['a', 'value1', 'value2'],
+        ],
+      },
+      sk,
+    )
+
+    expect(validateEvent(event)).toBe(false)
+  })
+
+  test('should return false when the "location" tag is missing', () => {
+    const sk = generateSecretKey()
+    const event: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: ClassifiedListing,
+        content:
+          'Lorem [ipsum][nostr:nevent1qqst8cujky046negxgwwm5ynqwn53t8aqjr6afd8g59nfqwxpdhylpcpzamhxue69uhhyetvv9ujuetcv9khqmr99e3k7mg8arnc9] dolor sit amet. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.\n\nRead more at nostr:naddr1qqzkjurnw4ksz9thwden5te0wfjkccte9ehx7um5wghx7un8qgs2d90kkcq3nk2jry62dyf50k0h36rhpdtd594my40w9pkal876jxgrqsqqqa28pccpzu.',
+        tags: [
+          ['d', 'sample-title'],
+          ['title', 'Sample Title'],
+          ['summary', 'Sample Summary'],
+          ['published_at', '1296962229'],
+          // Missing 'location' tag
+          ['price', '100', 'USD'],
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['t', 'tag1'],
+          ['t', 'tag2'],
+          ['e', 'value1', 'value2'],
+          ['a', 'value1', 'value2'],
+        ],
+      },
+      sk,
+    )
+
+    expect(validateEvent(event)).toBe(false)
+  })
+
+  test('should return false when the "price" tag is missing', () => {
+    const sk = generateSecretKey()
+    const event: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: ClassifiedListing,
+        content:
+          'Lorem [ipsum][nostr:nevent1qqst8cujky046negxgwwm5ynqwn53t8aqjr6afd8g59nfqwxpdhylpcpzamhxue69uhhyetvv9ujuetcv9khqmr99e3k7mg8arnc9] dolor sit amet. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.\n\nRead more at nostr:naddr1qqzkjurnw4ksz9thwden5te0wfjkccte9ehx7um5wghx7un8qgs2d90kkcq3nk2jry62dyf50k0h36rhpdtd594my40w9pkal876jxgrqsqqqa28pccpzu.',
+        tags: [
+          ['d', 'sample-title'],
+          ['title', 'Sample Title'],
+          ['summary', 'Sample Summary'],
+          ['published_at', '1296962229'],
+          ['location', 'NYC'],
+          // Missing 'price' tag
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['t', 'tag1'],
+          ['t', 'tag2'],
+          ['e', 'value1', 'value2'],
+          ['a', 'value1', 'value2'],
+        ],
+      },
+      sk,
+    )
+
+    expect(validateEvent(event)).toBe(false)
+  })
+
+  test('should return false when the "published_at" tag is not a valid timestamp', () => {
+    const sk = generateSecretKey()
+    const event: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: ClassifiedListing,
+        content: 'Lorem ipsum dolor sit amet.',
+        tags: [
+          ['d', 'sample-title'],
+          ['title', 'Sample Title'],
+          ['summary', 'Sample Summary'],
+          ['published_at', 'not-a-valid-timestamp'],
+          ['location', 'NYC'],
+          ['price', '100', 'USD'],
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['t', 'tag1'],
+          ['t', 'tag2'],
+        ],
+      },
+      sk,
+    )
+
+    expect(validateEvent(event)).toBe(false)
+  })
+
+  test('should return false when the "price" tag has not a valid price', () => {
+    const sk = generateSecretKey()
+    const event: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: ClassifiedListing,
+        content: 'Lorem ipsum dolor sit amet.',
+        tags: [
+          ['d', 'sample-title'],
+          ['title', 'Sample Title'],
+          ['summary', 'Sample Summary'],
+          ['published_at', '1296962229'],
+          ['location', 'NYC'],
+          ['price', 'not-a-valid-price', 'USD'],
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['t', 'tag1'],
+          ['t', 'tag2'],
+        ],
+      },
+      sk,
+    )
+
+    expect(validateEvent(event)).toBe(false)
+  })
+
+  test('should return false when the "price" tag has not a valid currency', () => {
+    const sk = generateSecretKey()
+    const event: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: ClassifiedListing,
+        content: 'Lorem ipsum dolor sit amet.',
+        tags: [
+          ['d', 'sample-title'],
+          ['title', 'Sample Title'],
+          ['summary', 'Sample Summary'],
+          ['published_at', '1296962229'],
+          ['location', 'NYC'],
+          ['price', '100', 'not-a-valid-currency'],
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['t', 'tag1'],
+          ['t', 'tag2'],
+        ],
+      },
+      sk,
+    )
+
+    expect(validateEvent(event)).toBe(false)
+  })
+
+  test('should return false when the "price" tag has not a valid number of elements', () => {
+    const sk = generateSecretKey()
+    const event1: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: ClassifiedListing,
+        content: 'Lorem ipsum dolor sit amet.',
+        tags: [
+          ['d', 'sample-title'],
+          ['title', 'Sample Title'],
+          ['summary', 'Sample Summary'],
+          ['published_at', '1296962229'],
+          ['location', 'NYC'],
+          ['price', '100'],
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['t', 'tag1'],
+          ['t', 'tag2'],
+        ],
+      },
+      sk,
+    )
+
+    expect(validateEvent(event1)).toBe(false)
+  })
+
+  test('should return false when the "a" tag has not a valid number of elements', () => {
+    const sk = generateSecretKey()
+    const event1: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: ClassifiedListing,
+        content: 'Lorem ipsum dolor sit amet.',
+        tags: [
+          ['d', 'sample-title'],
+          ['title', 'Sample Title'],
+          ['summary', 'Sample Summary'],
+          ['published_at', '1296962229'],
+          ['location', 'NYC'],
+          ['price', '100', 'USD'],
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['a', 'extra1'],
+          ['a', 'extra2', 'value2', 'extra3'],
+        ],
+      },
+      sk,
+    )
+
+    const event2: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: ClassifiedListing,
+        content: 'Lorem ipsum dolor sit amet.',
+        tags: [
+          ['d', 'sample-title'],
+          ['title', 'Sample Title'],
+          ['summary', 'Sample Summary'],
+          ['published_at', '1296962229'],
+          ['location', 'NYC'],
+          ['price', '100', 'USD'],
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['e', 'extra1'],
+          ['e', 'extra2', 'value2', 'extra3'],
+        ],
+      },
+      sk,
+    )
+
+    expect(validateEvent(event1)).toBe(false)
+    expect(validateEvent(event2)).toBe(false)
+  })
+})
+
+describe('parseEvent', () => {
+  test('should parse a valid event', () => {
+    const sk = generateSecretKey()
+    const event: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: DraftClassifiedListing,
+        content:
+          'Lorem [ipsum][nostr:nevent1qqst8cujky046negxgwwm5ynqwn53t8aqjr6afd8g59nfqwxpdhylpcpzamhxue69uhhyetvv9ujuetcv9khqmr99e3k7mg8arnc9] dolor sit amet. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.\n\nRead more at nostr:naddr1qqzkjurnw4ksz9thwden5te0wfjkccte9ehx7um5wghx7un8qgs2d90kkcq3nk2jry62dyf50k0h36rhpdtd594my40w9pkal876jxgrqsqqqa28pccpzu.',
+        tags: [
+          ['d', 'sample-title'],
+          ['title', 'Sample Title'],
+          ['summary', 'Sample Summary'],
+          ['published_at', '1296962229'],
+          ['location', 'NYC'],
+          ['price', '100', 'USD'],
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['t', 'tag1'],
+          ['t', 'tag2'],
+          ['e', 'value1', 'value2'],
+          ['a', 'value1', 'value2'],
+        ],
+      },
+      sk,
+    )
+
+    const expectedListing = {
+      title: 'Sample Title',
+      summary: 'Sample Summary',
+      publishedAt: '1296962229',
+      location: 'NYC',
+      price: {
+        amount: '100',
+        currency: 'USD',
+      },
+      images: [
+        {
+          url: 'https://example.com/image1.jpg',
+          dimensions: '800x600',
+        },
+        {
+          url: 'https://example.com/image2.jpg',
+        },
+      ],
+      hashtags: ['tag1', 'tag2'],
+      additionalTags: {
+        e: ['value1', 'value2'],
+        a: ['value1', 'value2'],
+      },
+      content:
+        'Lorem [ipsum][nostr:nevent1qqst8cujky046negxgwwm5ynqwn53t8aqjr6afd8g59nfqwxpdhylpcpzamhxue69uhhyetvv9ujuetcv9khqmr99e3k7mg8arnc9] dolor sit amet. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.\n\nRead more at nostr:naddr1qqzkjurnw4ksz9thwden5te0wfjkccte9ehx7um5wghx7un8qgs2d90kkcq3nk2jry62dyf50k0h36rhpdtd594my40w9pkal876jxgrqsqqqa28pccpzu.',
+      isDraft: true,
+    }
+
+    expect(parseEvent(event)).toEqual(expectedListing)
+  })
+
+  test('should throw an error for an invalid event', () => {
+    const sk = generateSecretKey()
+    const event: Event = finalizeEvent(
+      {
+        created_at: Math.floor(Date.now() / 1000),
+        kind: DraftClassifiedListing,
+        content:
+          'Lorem [ipsum][nostr:nevent1qqst8cujky046negxgwwm5ynqwn53t8aqjr6afd8g59nfqwxpdhylpcpzamhxue69uhhyetvv9ujuetcv9khqmr99e3k7mg8arnc9] dolor sit amet. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.\n\nRead more at nostr:naddr1qqzkjurnw4ksz9thwden5te0wfjkccte9ehx7um5wghx7un8qgs2d90kkcq3nk2jry62dyf50k0h36rhpdtd594my40w9pkal876jxgrqsqqqa28pccpzu.',
+        tags: [
+          // Missing 'd' tag
+          ['title', 'Sample Title'],
+          ['summary', 'Sample Summary'],
+          ['published_at', '1296962229'],
+          ['location', 'NYC'],
+          ['price', '100', 'USD'],
+          ['image', 'https://example.com/image1.jpg', '800x600'],
+          ['image', 'https://example.com/image2.jpg'],
+          ['t', 'tag1'],
+          ['t', 'tag2'],
+          ['e', 'value1', 'value2'],
+          ['a', 'value1', 'value2'],
+        ],
+      },
+      sk,
+    )
+
+    expect(() => parseEvent(event)).toThrow(Error)
+  })
+})
+
+describe('generateEventTemplate', () => {
+  test('should generate the correct event template for a classified listing', () => {
+    const listing: ClassifiedListingObject = {
+      title: 'Sample Title',
+      summary: 'Sample Summary',
+      publishedAt: '1296962229',
+      location: 'NYC',
+      price: {
+        amount: '100',
+        currency: 'USD',
+      },
+      images: [
+        {
+          url: 'https://example.com/image1.jpg',
+          dimensions: '800x600',
+        },
+        {
+          url: 'https://example.com/image2.jpg',
+        },
+      ],
+      hashtags: ['tag1', 'tag2'],
+      additionalTags: {
+        extra1: 'value1',
+        extra2: 'value2',
+      },
+      content:
+        'Lorem ipsum dolor sit amet. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.\n\nRead more at nostr:naddr1qqzkjurnw4ksz9thwden5te0wfjkccte9ehx7um5wghx7un8qgs2d90kkcq3nk2jry62dyf50k0h36rhpdtd594my40w9pkal876jxgrqsqqqa28pccpzu.',
+      isDraft: true,
+    }
+
+    const expectedEventTemplate = {
+      kind: DraftClassifiedListing,
+      content:
+        'Lorem ipsum dolor sit amet. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.\n\nRead more at nostr:naddr1qqzkjurnw4ksz9thwden5te0wfjkccte9ehx7um5wghx7un8qgs2d90kkcq3nk2jry62dyf50k0h36rhpdtd594my40w9pkal876jxgrqsqqqa28pccpzu.',
+      tags: [
+        ['d', 'sample-title'],
+        ['title', 'Sample Title'],
+        ['published_at', '1296962229'],
+        ['summary', 'Sample Summary'],
+        ['location', 'NYC'],
+        ['price', '100', 'USD'],
+        ['image', 'https://example.com/image1.jpg', '800x600'],
+        ['image', 'https://example.com/image2.jpg'],
+        ['t', 'tag1'],
+        ['t', 'tag2'],
+        ['extra1', 'value1'],
+        ['extra2', 'value2'],
+      ],
+      created_at: expect.any(Number),
+    }
+
+    expect(generateEventTemplate(listing)).toEqual(expectedEventTemplate)
+  })
+})