# London Mempool

> A free, verifiable map of London's best tech companies. 759 companies, mostly AI and fintech, plus quantum, crypto, defence, deeptech, health and climate. Every record is matched to Companies House where possible, and every claim links to a source.

- Updated: 2026-10-09
- Sectors (primary): AI 177, Fintech 195, Quantum 8, Crypto 33, Defence 18, Deeptech 28, Health 87, Climate 74, Other 139. 82 companies also have a secondary sector.
- Tiers: Well known 136, Fastest growing 215, Up and coming 408
- License: Free to use, including commercial use, with attribution to London Mempool (https://londonmempool.co.uk).
- Attribution: "Data from London Mempool (londonmempool.co.uk)"

## Who gets in

A tech company gets in if it is operating today, has a real office or a major team in London, clears one of the three stage bars below, and every fact about it can be backed by a public source.

- Well known (`well_known`): a household name in tech, or valued at $1B or more, or 500+ staff.
- Fastest growing (`fast_growing`): raised $20M or more in equity in the last 24 months, or grew 2x (revenue or headcount) in 2 years.
- Up and coming (`up_and_coming`): early stage, with real traction (customers, revenue or a product in use) or backing from top investors.

A company sits in the highest stage it qualifies for.

## How the data is verified

Each company is checked twice. The second check tries to prove the first one wrong. The legal entity is confirmed by its UK Companies House number (`ch_number`). The London address, funding and growth claims each carry a source URL (`address_source`, `funding_source`, `growth_source`). Facts that cannot be sourced are left out. Office pins come from the postcode via official ONS data (postcodes.io).

## Funding rounds

- `last_round`: the most recent funding round on record, as reported (e.g. "Series A, $30M, Jun 2026"), backed by `funding_source`.
- Read from that text only, never guessed: `last_round_month` (YYYY-MM, null without a month and year), `last_round_stage` (Pre-seed, Seed, Series A, Series B, Series C, Series D, Series E, Series F, Series G, Series H, Growth, IPO, Grant, Debt, Other; null when empty or not a raise, e.g. an acquisition), `last_round_kind` (equity, debt, mixed or grant; null when the instrument is unclear, e.g. a convertible note or bridge) and `last_round_amount` (`{value, currency}` only when exactly one exact figure is written; a currency conversion, a floor like $80M+ or "about" gives null).
- Filter `raised_since=YYYY-MM`: last round in or after that month and equity or mixed. It reads the latest round on record only, so it is not a full deal history.
- Rounds in the last 12 months, by month: https://londonmempool.co.uk/rounds

## Sectors

- `sector`: the primary sector. Map pins, stats and sector counts use it only, so counts add up to the total.
- `sector_secondary`: a second sector the company clearly also belongs to (e.g. Health for an AI drug discovery lab, Fintech for a regulated crypto exchange), or null. Never equal to `sector`, never Other. Hand-assigned from the company's own description; most companies have none.
- The `sector` filter (REST and MCP) matches either field. Add `primary_only=true` to match the primary sector only.

## Hiring and visas

- `open_roles_london`: open London roles counted from the company's public job board (Ashby, Greenhouse, Lever, Workable, Teamtailor, Personio), with `careers_url` and `roles_checked_at`. null means no public board was found, not that the company is not hiring.
- `work_model`: `onsite`, `hybrid` or `remote` when 80% or more of the company's London job posts with an explicit workplace type share it, `mixed` otherwise, with `work_model_roles` (how many typed posts it is based on; source is `careers_url`). Read only from the job board's own workplace field or a location that literally says Hybrid, Remote or On-site, never from description text. null under 2 typed posts. It reflects current job posts only, not company policy.
- `visa_sponsor`: true when the company is on the UK Home Office register of licensed Worker sponsors (exact legal name, or trading name for a London sponsor), with `visa_source` and `visa_register_name`. false means no exact match was found, not that the company never sponsors.

## Companies House

- `incorporated_on`: incorporation date of the legal entity (YYYY-MM-DD), read from the public Companies House register for `ch_number`. null when unknown.
- `ch_employees`: `{count, period_end, scope, source}`, the average number of employees during the accounting period ending `period_end`, as tagged in the latest annual accounts filed on Companies House (iXBRL filings only; `source` is the accounts document). `scope` is `company` for the registered company alone, `group` for a consolidated group figure, used only when the accounts give none for the company. It is a past average, so a floor for fast growers, and a UK subsidiary of a larger group counts only its own staff. null when no figure could be read. Separate from `employees` (the reported headcount bucket). Filter: `min_staff`.
- `sic_codes`: SIC 2007 codes listed on Companies House as the nature of business. Empty when unknown.

## London presence

- `presence`: `hq` (main or global HQ in London), `office` (a London office, HQ elsewhere) or `people` (London staff, no office), with `presence_source`. null means not yet checked.

## Nearest station

- `nearest_station`: the closest TfL rail station (Underground, Elizabeth line, DLR or Overground) to the office postcode, from TfL open data, with `station_distance_m` (straight-line metres, walking is longer). Companies grouped by station: https://londonmempool.co.uk/tube

## Context places

55 London landmarks to read the map against: VCs 31, Big tech 7, Universities 7, Accelerators 2, Coworking 8. Each has `id`, `name`, `type` (vc, bigtech, university, accelerator, coworking), `address`, `postcode`, `borough`, `lat`/`lng`, `source_url` (a page that shows the address), optional `ch_number` and `verified_on`. They are not companies in the dataset and are not ranked. All of them: `GET https://londonmempool.co.uk/places.json`, or the MCP tool `list_places` with an optional `type`.

## Investors

- `investors`: institutional investors named as backing the company on a page we fetched, each `{name, slug, lead, source}`. `lead` = the source says it led a round. Angels, grants and lenders are left out. It is a floor, not a full cap table: an empty array means none were found.
- `github_org`: GitHub organisation login linked from the company's own home page and confirmed on the public GitHub API, with `github_source` (the company page that links it). Profile: https://github.com/{github_org}. null means no link was found on the home page, not that the company publishes no open source.
- `accelerators`: accelerator programmes the company went through, each `{program, batch, source}`, from the programme's own public list matched by the company's website domain: Y Combinator (batch like W24, S21, F24 = Fall, X25 = Spring; source is the company's ycombinator.com/companies page), Antler, Founders Factory and Conception X (cohort like CX24 when shown, else null). Programmes without a public list of company websites (Entrepreneur First, Techstars) are not covered, so an empty array means none of these lists names the company.
- `cohorts`: published recognition lists the company appears on, newest first, each `{list, year, rank, source}`: Sifted 100 UK & Ireland, Tech Nation Future Fifty, Tech Nation Upscale, Deloitte UK Technology Fast 50, LinkedIn Top Startups UK, Forbes AI 50. `rank` is the position on a ranked list, null on an unranked one; `source` is the publisher's own list (page, PDF or Forbes' list API). Matched by website or LinkedIn page, or by exact name plus a location on the list; uncertain matches are left out, so an empty array means none of the editions we read names the company.
- `ecosystems`: crypto companies only. The blockchains the product is built on or primarily supports, each `{name, source}`, where `source` is the company's own site, docs, GitHub or announcement naming the chain. Names come from a fixed list (Ethereum, Bitcoin, Solana, XRP Ledger, Tezos, Starknet and others). Multi-asset exchanges, custodians, brokers and payment rails stay empty, as do companies whose own pages name no chain, so an empty array is not a claim that a company uses no chain.
- Leaderboard of investors by companies on the map: https://londonmempool.co.uk/investors, one page per investor with 2 or more at https://londonmempool.co.uk/investors/{slug}. As JSON: `GET https://londonmempool.co.uk/investors.json`, or the MCP tool `list_investors`.

## How to query

No key needed. CORS is open. All responses are JSON.

- Search: `GET https://londonmempool.co.uk/api/v1/companies` with any of: `sector` (AI, Fintech, Quantum, Crypto, Defence, Deeptech, Health, Climate, Other; comma-separated for several; matches primary or secondary sector), `primary_only` (true = sector filter checks the primary sector only), `tier` (well_known, fast_growing, up_and_coming), `borough`, `area` (tech neighbourhood slug, e.g. kings-cross; list in meta), `q` (text search over name, subsector and description), `min_funding_usd`, `min_staff` (at least this many average employees in the latest Companies House accounts), `founded_after` (strictly after that year), `raised_since` (YYYY-MM; last round in or after that month and equity or mixed), `hiring` (true = open London roles), `visa_sponsor` (true = licensed visa sponsor), `open_source` (true = GitHub organisation linked from the company's site), `presence` (hq, office, people; comma-separated for several), `work_model` (onsite, hybrid, remote; from current London job posts; comma-separated for several), `investor` (investor slug, e.g. index-ventures; comma-separated for several), `accelerator` (y-combinator, antler, founders-factory, conception-x; comma-separated for several), `cohort` (sifted-100-uk-ireland, tech-nation-future-fifty, tech-nation-upscale, deloitte-uk-fast-50, linkedin-top-startups-uk, forbes-ai-50; any edition year; comma-separated for several), `ecosystem` (blockchain slug: ethereum, bitcoin, solana, polygon, base, arbitrum, optimism, avalanche, cosmos, polkadot, stellar, xrp-ledger, tezos, cardano, ton, sui, aptos, near, bnb-chain, starknet, zksync, plasma; comma-separated for several), `sort` (name, funding, founded), `order` (asc, desc), `limit` (default 20, max 500), `offset`.
- Example: `GET https://londonmempool.co.uk/api/v1/companies?sector=AI&tier=fast_growing&sort=funding&limit=10`
- One company: `GET https://londonmempool.co.uk/api/v1/companies/{id}`
- Counts and field descriptions: `GET https://londonmempool.co.uk/api/v1/meta`
- What changed: `GET https://londonmempool.co.uk/changes.json`, or the MCP tool `list_changes` with an optional `since` date (YYYY-MM-DD)

## Endpoints

- [REST search](https://londonmempool.co.uk/api/v1/companies): filter, sort and page companies
- [Dataset metadata](https://londonmempool.co.uk/api/v1/meta): counts by sector, tier, borough and area, plus every field explained
- [OpenAPI 3.1 spec](https://londonmempool.co.uk/openapi.json): machine-readable description of the REST API
- [Full dataset (JSON)](https://londonmempool.co.uk/companies.json): every company in one file
- [Full dataset (CSV)](https://londonmempool.co.uk/london-mempool.csv): the same data as a spreadsheet
- [Context places (JSON)](https://londonmempool.co.uk/places.json): VCs, big tech, universities, accelerators and coworking spaces, with sources. Not ranked
- [Investors (JSON)](https://londonmempool.co.uk/investors.json): every investor named in a source, with company counts, leads and company ids
- [Changelog (JSON)](https://londonmempool.co.uk/changes.json): every company added, removed or updated, one entry per day, newest first
- [Changelog (RSS)](https://londonmempool.co.uk/feed.xml): the same log as a feed
- [MCP server](https://londonmempool.co.uk/mcp): Streamable HTTP, tools search_companies, get_company, list_sectors, list_changes, list_places, list_investors, get_dataset_info. Add to Claude Code with `claude mcp add --transport http london-mempool https://londonmempool.co.uk/mcp`
- [Developer docs](https://londonmempool.co.uk/developers): examples for curl and MCP clients
- [How we verify](https://londonmempool.co.uk/methodology): selection and verification method
- [Investor leaderboard](https://londonmempool.co.uk/investors): investors ranked by companies on the map
- [Recent rounds](https://londonmempool.co.uk/rounds): the latest round on record for each company, last 12 months, grouped by month
- [Tube map](https://londonmempool.co.uk/tube): companies grouped by their nearest station, Zone 1 and 2
- [Tech neighbourhoods](https://londonmempool.co.uk/areas): companies by area (King's Cross, Shoreditch & Old Street, Canary Wharf and more), one page per area at https://londonmempool.co.uk/area/{slug}
- [Notes](https://londonmempool.co.uk/notes): short notes on patterns in the data, every number computed from the dataset at build time
  - [Where each sector clusters](https://londonmempool.co.uk/notes/where-sectors-cluster): 14 of the 33 Crypto companies on London Mempool are in City & Bank, the highest share in one neighbourhood of any sector with 20 or more.
  - [How young each sector is](https://londonmempool.co.uk/notes/how-young-each-sector-is): 64 of the 105 companies on London Mempool incorporated in 2023 or later are AI.
  - [Investors that stick to one sector](https://londonmempool.co.uk/notes/investors-that-stick-to-one-sector): Lowercarbon Capital is the most focused of the 61 investors with 6 or more companies on London Mempool: 6 of 6 are Climate.
  - [The stations closest to London tech](https://londonmempool.co.uk/notes/stations-closest-to-london-tech): Old Street is the nearest station for 101 companies on London Mempool, 2.5 times as many as Chancery Lane in second place.

## Optional

- [llms-full.txt](https://londonmempool.co.uk/llms-full.txt): every company as one markdown line