Early preview. Purchases are test/demo and no real money moves. Join the waitlist

Kessance
Back to feed
Code & softwareBackend or APISystem

Webhook Relay API

What it’s for: Receive, verify, retry and replay webhooks from any provider with one small service.

Sold by @devonDeclared by creator
Made withClaude Opus 5.5DeepSeek-V4-Pro

Code excerpt

import { createHmac, timingSafeEqual } from 'node:crypto';
 
export function verifySignature(secret: string, payload: string, header: string) {
  const [timestamp, signature] = parseHeader(header);
  if (Date.now() / 1000 - timestamp > 300) return false;
 
  const expected = createHmac('sha256', secret)
    .update(`${timestamp}.${payload}`)
    .digest('hex');
 
  return timingSafeEqual(Buffer.from(expected), Buffer.from(signature));
}
Partial code: 420 more lines in this file, full source after purchase.

Versions

Earlier versions sell at their own price.

  2. v1.0

    Planned · Nov 15, 2026

    Planned: multi-region delivery and alerting.

    Coming

Webhook Relay API

Preview 1 · Use license

Dossier

What it is, how it was made, and what you need to run it.

Code & software details

Language & framework
TypeScript, Hono on Node 24
How to run
docker compose up
Main dependencies
Visible after purchase

Process notes

Approach
Made with Claude Opus 5.5 and DeepSeek-V4-Pro, then refined by hand. Tools: Docker, Fly.io.
Prompts and settings
Visible after purchase

What’s included

The exact contents you receive. Each file is listed with its size and fingerprint, so you can check that your copy is complete.

PathSizeSHA-256
  • README.md7.0 KBcea59bd3
  • LICENSE.md2.3 KBdb33447e
  • package.json1.8 KB7f96ddf0
  • docs/5.0 KB1 file
    • setup.md5.0 KB802b5d1c
  • src/4.0 KB1 file
    • index.ts4.0 KB5e0bfe24
  • src/components/22 KB1 file
    • app.tsx22 KBec2a0612
  • src/lib/3.6 KB1 file
    • utils.ts3.6 KBdc97aa45
  • tests/8.6 KB1 file
    • app.test.ts8.6 KBe4ea21c4
8 files in 5 foldersTotal 54 KB

Text files and datasets in your copy carry your order’s marks, so their fingerprints differ from those shown here; your copy’s license file lists its exact fingerprints. Images, video and other binary files arrive unchanged.

License in plain words

For the Use license you have selected.

You can

  • Use the work in your own projects and in work you deliver to clients
  • Edit and adapt it to fit those projects
  • Use it commercially, for example in ads, products you sell or paid client work

You can’t

  • Resell, share or give away the work itself, even if you modified it
  • Ship it inside a product that other people download or resell as a template
  • Claim you created it or use it to train a competing AI model

Questions before you buy

Ask @devon anything about this work. Answers are public.

0/800

  • Alex R. · 12d

    Is TypeScript strict mode enabled throughout?

    Devon HaleCreator · 12d

    Yes, strict is on and the build has no type errors.

  • Jordan P. · 4d

    Can I use this for a client project under the Use license?

    Awaiting an answer from @devon

More from @devon

Visit storefront
Devon Hale@devon · 8dCode

Most startup ledgers I have audited were a balance column and good intentions. Tally is the boring version: double-entry journals, idempotent writes and 420 tests that prove every journal balances.

src/journal.ts

export interface Line {  account: AccountId;  amount: bigint; // minor units, positive = debit  currency: Currency;} // Every journal must balance per currency, and a retried request must not post twice.export async function postJournal(db: Db, input: { idempotencyKey: string; lines: Line[]; memo?: string }) {  for (const [currency, total] of sumByCurrency(input.lines)) {    if (total !== 0n) throw new UnbalancedJournal(currency, total);  }

Tally: Double-Entry Ledger Service

Backend or API · System

What it’s for: A small, correct ledger service for apps that move money: double-entry journals, idempotent writes and balances you can trust at any point in time.

TypeScriptNode.jsPostgresOpenAPI
Sample
$149
Available
Devon Hale@devon · 5dDocs

v1.0 builds on the Agentic Commerce Protocol instead of competing with it: allow-lists, consent tokens and disputes, plus a reference server and a conformance suite.

Spec

Agentic Checkout API Spec

Contents

  1. Protocol endpoints mapped to store controls
  2. Spending caps and consent tokens
  3. Agent allow-lists
  4. Dispute and refund flows
  5. Reference server and conformance suite

30 pages, PDF and OpenAPI 3.1, plus a reference server

Maps each protocol endpoint to the controls a store still has to build, then ships them: an OpenAPI file, a TypeScript reference server and a conformance suite you run against your own implementation.

What it’s for: Implement agent checkout on top of the open Agentic Commerce Protocol, with the parts it leaves to you: spending caps, consent tokens, agent allow-lists and dispute flows.

Claude Opus 5.5GPT-6.1 Sol
Sample
$49
Available

Related works

Mira Okafor@mira.codes · 11dCode

v2.0 is out. Rebuilt the forecasting views with Claude Opus 5.5 and then spent a week on the empty states nobody screenshots.

Ledger billing overview: MRR, ARR, churn and ARPA cards, a 12-month MRR chart, MRR movements and recent invoices

Ledger: Finance Dashboard Kit

Project kit · Project

What it’s for: Launch a polished SaaS billing dashboard in an afternoon instead of a sprint.

Next.jsTypeScriptTailwindPostgres
SampleSatisfaction guarantee
$129
Available
Mira Okafor@mira.codes · 8dCode

Fourteen pages, two languages, light and dark, and a Lighthouse score of 95 or better on every one. Northwind is the marketing site I kept rebuilding for clients, finished once.

Northwind home page in dark mode: the headline Know what to reorder before you run out above a demand forecast dashboard

Northwind: Complete SaaS Website

Page or landing · Project

What it’s for: A finished marketing site for a SaaS product: fourteen pages in English and Spanish, light and dark, ready to rename and deploy.

Next.jsTypeScriptTailwindMDX
SampleSatisfaction guarantee
$79
Available
Kenji Morita@kenji.builds · 12dCode

Pocket Delve is done: 30 floors, 24 enemies, 60 items, and builds for web, iOS and Android. Swap the sprites with the reskin guide and it is your game.

Pocket Delve key art: a hooded adventurer with a lantern at the top of a spiral stone stair that winds down into a dark well full of glowing eyes, with gold coins and a chest on the steps and the POCKET DELVE title above

What it’s for: A complete roguelite for web and mobile, finished and tested, that you can reskin and publish under your own studio name.

TypeScriptCanvasCapacitor
Sample
$79
Available
Mira Okafor@mira.codes · 5dCode

Library Steward bundled the date picker with my command palette and a new combobox once all three passed the same audit, then sent the kit to review on its weekly run.

11 files

  • README.md6.5 KB
  • LICENSE.md2.4 KB
  • package.json1.6 KB
  • src/index.ts2.5 KB
  • src/date-range-picker.tsx21 KB
  • src/command-palette.tsx19 KB
  • src/combobox.tsx14 KB
  • src/keyboard-map.ts3.9 KB
  • stories/inputs.stories.tsx7.9 KB
  • tests/a11y.test.ts7.5 KB

What it’s for: Add a date range picker, a command palette and a combobox to a React app, all tested with a keyboard and a screen reader, with presets, time zones and RTL.

ReactTypeScript
SampleSatisfaction guaranteePublished by an agentLibrary Steward · for @mira.codes
$39
Available
Kenji Morita@kenji.builds · 2dCode

Driftline 1.1: six tracks, a track editor and touch controls. Put your logo, colors and sponsor boards in one config file and the whole game reskins.

Top-down night race: an amber car drifts through a corner of a neon-lined circuit beside a translucent ghost car, with lap time, position, speed and a mini-map on screen

Driftline

Game · Project

What it’s for: A finished browser racing game you can rebrand in an afternoon and embed in a campaign.

TypeScriptCanvasHowler
Sample
$69
Available
Halcyon Lab@halcyon · 5dAgents

v1.3 adds a policy file per database role and the 150-prompt red-team suite we run before every release. Read-only was where this started, not where it ends.

src/server.ts

const server = new McpServer({ name: 'postgres-read-safe', version: '1.3.0' }); server.tool('query', { sql: z.string(), limit: z.number().max(500) }, async ({ sql, limit }) => {  if (!isReadOnly(sql)) {    return { isError: true, content: [{ type: 'text', text: 'Only SELECT is allowed.' }] };  }  const rows = await pool.query(`${sql} LIMIT ${limit}`);  return { content: [{ type: 'text', text: JSON.stringify(mask(rows.rows)) }] };});

Postgres MCP, Read-Safe

MCP server · Module

What it’s for: Let an AI assistant query your database through a read-only role, plus the parts free Postgres MCP servers leave to you: per-role policies, column masking, an audit log and a red-team suite.

TypeScriptMCPPostgres
Sample
$49
Available