* perf: read global_settings once per settings-load pass `initial_load` reads several dozen settings back to back, one `SELECT value FROM global_settings WHERE name = $1` each: 50 serialized round trips before a worker is ready, 32 before a server is. On localhost that is ~20ms and invisible; against a real database it is 50x the RTT per process start, which `EXIT_AFTER_N_JOBS` turns into a per-job cost. `with_global_settings_snapshot` reads the whole table (12 rows on a typical instance) into a tokio task-local, and `load_value_from_global_settings` serves from it. Scoping it to the task is what keeps the single-setting reload paths correct: a `notify_global_setting_change` event for one key runs outside any scope and still reads the database, so a live settings change reaches a running worker as before. Agent workers hold an HTTP connection with no snapshot to take and are unchanged. `load_smtp_config` and `reload_custom_tags_setting` had their own inline copies of the same query; they go through the shared loader so they land in the snapshot too. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * docs: state the snapshot contract on the reader and the query `load_value_from_global_settings` is called from ~10 crates and one of them writes a setting then immediately re-reads it through `reload_custom_tags_setting`; say on the function itself that a scope, when one is installed, serves the read and leaves `db` unused. The query comment claimed the table is a handful of rows. It is not bounded that way: `workspace_dependencies_map_rebuilt:<workspace_id>` adds a row per workspace and never removes it. Those dynamically named rows are also why the snapshot fetches the whole table instead of the wanted names, so state that as the reason. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix: bound the settings snapshot and keep it out of two reads Three review findings, all real: The snapshot fetched the whole table, which is not bounded by the settings that exist: `workspace_dependencies_map_rebuilt:<workspace_id>` adds a row per workspace with no cleanup path, and no settings pass reads one. It now fetches only statically named rows, and reads of a `<prefix>:<id>` name skip the snapshot and go to the database. Correctness does not rest on that naming convention — a colon-free dynamic name would simply be in the snapshot and still answered correctly — only the bound does. A snapshot query that failed inside an enclosing snapshot awaited the body bare, so its reads were served by the outer snapshot rather than falling through as documented. The task-local carries an explicit bypass state and the failure path scopes it. `reload_jwt_secret_setting` decided whether to generate-and-upsert the JWT secret from a snapshot-served read, so a replica booting alongside another could overwrite the secret it had just generated and invalidate its tokens. That read goes through the new `load_value_from_global_settings_fresh`. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix: keep the snapshot query on the primary-key index `name NOT LIKE '%:%'` bounded the rows returned but not the work: a leading wildcard cannot use the index, so Postgres read every row anyway. Against 50k dynamically named rows it plans as a seq scan of 516 buffers whether or not seqscans are enabled — and worker connections disable them, so the plan was one the query shape forbade rather than one the planner chose. `name = ANY($1)` over an explicit list plans as a bitmap index scan, 7 buffers, bounded by the listed names rather than by table size. That list is also exactly the set the snapshot may answer from, so a name outside it falls through to the database instead of reading as unset: listing a setting is a performance choice, never a correctness one, which is what keeps the list safe to maintain by hand. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * refactor: declare a settings pass instead of reading one setting at a time Replaces the prefetch-list snapshot with a pass the call sites build themselves. `SettingsPass` collects the reads `initial_load` will make as `(name, applier)` pairs, fetches them together, then replays the appliers in declaration order. Declaring is what makes the batch exact. The same `if server_mode` / `if *CLOUD_HOSTED` / `cfg` branches that used to guard a read now guard a declaration, so the fetch asks for what this process needs and nothing else, and there is no list of setting names to keep in sync with anything. Ordering is preserved end to end: appliers run in the order they were declared, and non-setting work in the middle of the sequence keeps its place as a step, so nothing moves and nothing runs twice. Steps that need several settings at once take them together. The batch distinguishes three states where a per-setting read only ever produced two at a given call site: - a value, - genuinely unset, which several settings must see in order to restore a default when the setting is cleared, - could not be read, which must leave the in-memory value alone. Collapsing this into "unset" would let one failed query reset workspace fairness and the queue caps across a cluster. Over HTTP the reads go out together rather than sequentially, so an agent worker's settings load costs one round instead of ~36, with no new endpoint. A setting an agent may not request still resolves to unset, as the per-setting call returned for it. `reload_*` keeps working per setting for the notify path, sharing its apply half with the pass. The wrappers no caller was left using are dropped. worker startup: 50 queries -> 2 (the batch, and jwt_secret which stays its own read so the pass cannot sit between reading it absent and upserting a replacement over another replica's). Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix: run the pass's non-setting steps in declaration order too Review round found the settings pass had a gap: the reads were declared but the work interleaved between them still awaited inline, so it all ran before `pass.run` applied anything. `manage_audit_partitions` therefore saw `AUDIT_LOG_RETENTION_DAYS` at its compile-time default rather than the configured value, and dropped every partition past that default. An instance keeping 30 days on CE lost the 14-to-30-day band on startup and on every full-reload tick. The `STORE_AUDIT_LOGS_S3` export anchor had the same cause: the gate read `false` before the setting applied, so an env-var-enabled export never anchored and its first tick skipped the rows committed before it. `action` exists so a step keeps its place in the sequence; every remaining inline await is now one, which fixes both and leaves no phase where a read can observe a value the pass has not applied yet. Two more from the same round: A batch that fails as a whole now falls back to per-setting reads. Skipping every applier preserves known-good state on a reload tick, but a starting process has none, and would have run on compile-time defaults until the next full reload twelve hours later. `FORCE_RUBY_REPOS` is honored again: the batched url-list path parsed without the `FORCE_` check its per-setting counterpart applied, so the override was silently dropped. `load_setting_value` never had one, so the third helper was never affected. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix: declare the object-store and worker-config steps in the pass too Two awaits were left running ahead of `pass.run`, so the settings they read were still at their compile-time defaults. The object-store reload is the one that matters: an AWS OIDC store mints its first token against an issuer built from `BASE_URL` (`oidc_ee.rs`), and with `OTEL_ENVIRONMENT` set nothing loads that before this pass does, so the store signed with the unset default, left `OBJECT_STORE_SETTINGS` empty and fell back to the ten-second retry while startup carried on. `reload_worker_config` calls `store_pull_query`, which reads the workspace fairness knobs. It happened to converge because the enabled flag re-stores the query when it changes, but it was reading defaults on the way there. Both are steps now, which is also what the earlier fix should have covered: the only await left outside a step is `pass.run` itself. Also from the same round: `fetch_settings_batch`'s doc comment had been stranded on the helper inserted above it, and the batch-failure fallback re-ran the same reads on an agent worker, where the batch already is the per-setting read. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * docs: point the setting-loader docs at functions that still exist `reload_setting` went with the other wrappers no caller was left using, but two doc links still referenced it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix: decide the jwt secret in sql so the read can be batched `reload_jwt_secret_setting` generated a secret whenever its read came back absent or unparseable, and upserted it unconditionally. Two replicas booting against an empty row therefore each installed their own and rejected each other's tokens, and the same happened on a running cluster whenever the row was deleted or set to a non-string. Keeping the read next to the write kept the window narrow but never closed it, and it was the reason this one setting could not go through the settings pass. `get_or_create_jwt_secret` puts the decision in the statement instead: INSERT ... ON CONFLICT (name) DO UPDATE SET value = EXCLUDED.value WHERE jsonb_typeof(global_settings.value) <> 'string' RETURNING value First writer wins, a usable secret is never overwritten, and an empty RETURNING is how a caller learns another process's secret stands. The `WHERE` also keeps a normal startup from writing at all, which matters because `notify_global_setting_change` fires on every write to this table and an unconditional upsert would have made each start trigger a cluster-wide reload. Because the statement decides rather than the caller's read, a stale value is harmless and `jwt_secret` is now an ordinary declaration. Worker startup is a single batch round. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix: keep a failed read from dropping a FORCE_ override or clearing a setting Two ways a read that did not succeed was being treated as an answer. A `FORCE_` override used to be checked before the read, so a failed read could not affect it. Moving that check into the parser put it behind a value arriving, and a failed read skips its applier, so a forced private registry fell back to the public index and a forced `settings.xml` was deleted from disk by the Maven step that follows it. Forced settings are declared as steps with no read now: the override outranks the database, so there is nothing to fetch and nothing to lose when a fetch fails. The setting loaders were passing `v.ok().flatten()` to their appliers, which turns a database error into "unset". Most appliers ignore `None`, but `apply_tag_per_workspace_workspaces` clears the workspace whitelist with it, making every workspace eligible for per-workspace tags, and `apply_fork_workspace_tag_append_fork_suffix` stores `false`. Both are also reached from the notify handlers, so a blip during a reload changed routing for the cluster. They take `?` now, as the code they replaced did by leaving the error arm empty, and the other five are converted with them so an applier that later grows a `None` branch cannot inherit the problem. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix: route hub_api_secret through the FORCE-aware declaration `HUB_API_SECRET` lives in an `ArcSwap` rather than an `Arc<RwLock<_>>`, so it could not use `option_setting` and was declared by hand with a bare `setting` plus `parse_option_setting_value` — which is exactly the path that skips the `FORCE_` handling, so a failed read still dropped `FORCE_HUB_API_SECRET`. The rule now lives in `option_setting_with`, which takes the store closure and leaves `option_setting` a wrapper over it, so a setting held in something other than an `RwLock` reaches it too rather than having to reimplement it. The three remaining hand-written parses are `parse_setting_value`, which has no `FORCE_` handling to miss: `load_setting_value` never had the check either. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
Open-source developer platform for internal code: APIs, background jobs, workflows and UIs. Self-hostable alternative to Retool, Pipedream, Superblocks and a simplified Temporal with autogenerated UIs and custom UIs to trigger workflows and scripts as internal apps.
Scripts are turned into sharable UIs automatically, and can be composed together into flows or used into richer apps built with low-code. Supported languages: Python, TypeScript, Go, Bash, SQL, GraphQL, PowerShell, Rust, and more.
Try it - Website - Docs - Discord - Hub - Contributor's guide
Windmill - Developer platform for APIs, background jobs, workflows and UIs
Windmill is fully open-sourced (AGPLv3) and Windmill Labs offers dedicated instances and commercial support and licenses.
https://github.com/user-attachments/assets/d80de1d9-64de-4d89-aacd-6df23fa81fc4
- Windmill - Developer platform for APIs, background jobs, workflows and UIs
Main Concepts
- Define a minimal and generic script in Python, TypeScript, Go or Bash that solves a specific task. The code can be defined in the provided Web IDE or synchronized with your own GitHub repo (e.g. through VS Code extension): provided Web IDE or synchronized with your own GitHub repo (e.g. through VS Code extension):
- Your scripts parameters are automatically parsed and generate a frontend.
- Make it flow! You can chain your scripts or scripts made by the community shared on WindmillHub.
- Build complex UIs on top of your scripts and flows.
Scripts and flows can be triggered by schedules, webhooks, HTTP routes, Kafka, WebSockets, emails, and more.
Build your entire infra on top of Windmill!
Show me some actual script code
//import any dependency from npm
import * as wmill from "windmill-client";
import * as cowsay from "cowsay@1.5.0";
// fill the type, or use the +Resource type to get a type-safe reference to a resource
type Postgresql = {
host: string;
port: number;
user: string;
dbname: string;
sslmode: string;
password: string;
};
export async function main(
a: number,
b: "my" | "enum",
c: Postgresql,
d = "inferred type string from default arg",
e = { nested: "object" }
//f: wmill.Base64
) {
const email = process.env["WM_EMAIL"];
// variables are permissioned and by path
let variable = await wmill.getVariable("f/company-folder/my_secret");
const lastTimeRun = await wmill.getState();
// logs are printed and always inspectable
console.log(cowsay.say({ text: "hello " + email + " " + lastTimeRun }));
await wmill.setState(Date.now());
// return is serialized as JSON
return { foo: d, variable };
}
Local Development
Windmill supports multiple ways to develop locally and sync with your instance:
| Tool | Description |
|---|---|
| CLI | Sync scripts from local files or GitHub, run scripts/flows from the command line |
| VS Code Extension | Edit and test scripts & flows directly from VS Code / Cursor with full IDE support |
| Git Sync | Two-way sync between Windmill and your Git repository |
| Claude Code | AI-assisted development with Claude for scripts, flows, and apps |
https://github.com/user-attachments/assets/c541c326-e9ae-4602-a09a-1989aaded1e9
You can run scripts locally by passing the right environment variables for the wmill client library to fetch resources and variables from your instance. See local development docs.
Stack
- Database: Postgres (compatible with Aurora, Cloud SQL, Neon, Azure PostgreSQL)
- Backend: Rust - stateless API servers and workers pulling jobs from a Postgres queue
- Frontend: Svelte 5
- Sandboxing: nsjail and PID namespace isolation
- Runtimes:
- TypeScript/JavaScript: Bun (default) and Deno
- Python: python3 with uv for dependency management
- Go, Bash, PowerShell, PHP, Rust, C#, Java, Ansible
Fastest Self-Hostable Workflow Engine
We have compared Windmill to other self-hostable workflow engines (Airflow, Prefect & Temporal) and Windmill is the most performant solution for both benchmarks: one flow composed of 40 lightweight tasks & one flow composed of 10 long-running tasks.
All methodology & results on our Benchmarks page.
Security
- Sandboxing: nsjail for filesystem/resource isolation, and PID namespace isolation (enabled by default) to prevent jobs from accessing worker process memory
- Secrets: One encryption key per workspace for credentials stored in Windmill's K/V store. We recommend encrypting the Postgres database as well.
See Security documentation for details.
Performance
Once a job started, there is no overhead compared to running the same script on the node with its corresponding runner (Deno/Go/Python/Bash). The added latency from a job being pulled from the queue, started, and then having its result sent back to the database is ~50ms. A typical lightweight deno job will take around 100ms total.
Architecture
How to self-host
For detailed setup options, see Self-Host documentation.
Docker compose
Deploy Windmill with 3 files (docker-compose.yml, Caddyfile, .env):
curl https://raw.githubusercontent.com/windmill-labs/windmill/main/docker-compose.yml -o docker-compose.yml
curl https://raw.githubusercontent.com/windmill-labs/windmill/main/Caddyfile -o Caddyfile
curl https://raw.githubusercontent.com/windmill-labs/windmill/main/.env -o .env
docker compose up -d
Go to http://localhost - default credentials: admin@windmill.dev / changeme
Using an external database: Set DATABASE_URL in .env to point to your managed Postgres (AWS RDS, GCP Cloud SQL, Azure, Neon, etc.) and set db replicas to 0.
Kubernetes (Helm charts)
helm repo add windmill https://windmill-labs.github.io/windmill-helm-charts/
helm install windmill-chart windmill/windmill --namespace=windmill --create-namespace
See windmill-helm-charts for configuration options.
Cloud providers
Windmill works on AWS (EKS/ECS), GCP, Azure, Ubicloud, Fly.io, Render.com, Hetzner, Digital Ocean, and others. Rule of thumb: 1 worker per 1vCPU and 1-2 GB RAM.
OAuth, SSO & SMTP
Configure OAuth and SSO (Google Workspace, Microsoft/Azure, Okta) directly from the superadmin UI. See documentation.
License
The Community Edition is free to use internally. For commercial redistribution or managed services, contact sales@windmill.dev. See LICENSE and Pricing for details.
The "Community Edition" of Windmill available in the docker images hosted under ghcr.io/windmill-labs/windmill and the github binary releases contains the files under the AGPLv3 and Apache 2 sources but also includes proprietary and non-public code and features which are not open source and under the following terms: Windmill Labs, Inc. grants a right to use all the features of the "Community Edition" for free without restrictions other than the limits and quotas set in the software and a right to distribute the community edition as is but not to sell, resell, serve Windmill as a managed service, modify or wrap under any form without an explicit agreement.
The binary compilable from source code in this repository without the "enterprise" feature flag is open-source under the LICENSE-AGPLv3 License terms and conditions.
To re-expose directly any Windmill parts to your users as a feature of your product, with the exception of iframed public Windmill "apps", or to build a feature on top of "Windmill Community Edition" that you sell commercially or embed in a distributable product or binary, you must get a commercial license. Contact us at sales@windmill.dev if you have any questions. To do the same from the binary compiled from the source code in this repository without the "enterprise" feature flag, you must comply with the AGPLv3 license terms and conditions or get a commercial license from Windmill Labs, Inc.
To use Windmill "Community Edition" as is internally in your organization, or to use its APIs as is, you do NOT need a commercial license.
Integrations
In Windmill, integrations are referred to as resources and resource types. Each Resource has a Resource Type that defines the schema that the resource needs to implement.
On self-hosted instances, you might want to import all the approved resource types from WindmillHub. A setup script will prompt you to have it being synced automatically everyday.
Environment Variables
| Environment Variable name | Default | Description | Api Server/Worker/All |
|---|---|---|---|
| DATABASE_URL | The Postgres database url. | All | |
| WORKER_GROUP | default | The worker group the worker belongs to and get its configuration pulled from | Worker |
| MODE | standalone | The mode if the binary. Possible values: standalone, worker, server, agent | All |
| METRICS_ADDR | None | (ee only) The socket addr at which to expose Prometheus metrics at the /metrics path. Set to "true" to expose it on port 8001 | All |
| JSON_FMT | false | Output the logs in json format instead of logfmt | All |
| BASE_URL | http://localhost:8000 | The base url that is exposed publicly to access your instance. Is overriden by the instance settings if any. | Server |
| ZOMBIE_JOB_TIMEOUT | 30 | The timeout after which a job is considered to be zombie if the worker did not send pings about processing the job (every server check for zombie jobs every 30s) | Server |
| RESTART_ZOMBIE_JOBS | true | If true then a zombie job is restarted (in-place with the same uuid and some logs), if false the zombie job is failed | Server |
| NATIVE_MODE | false | Enable native mode: sets NUM_WORKERS=8, rejects non-native jobs (nativets, postgresql, mysql, etc.) | Worker |
| SLEEP_QUEUE | 50 | The number of ms to sleep in between the last check for new jobs in the DB. It is multiplied by NUM_WORKERS such that in average, for one worker instance, there is one pull every SLEEP_QUEUE ms. | Worker |
| KEEP_JOB_DIR | false | Keep the job directory after the job is done. Useful for debugging. | Worker |
| EXIT_AFTER_N_JOBS | None | Exit the worker process after it has executed that many jobs, so that a supervisor restarts it and no process runs more than that many, bar the steps of a same-worker flow it has started, which it always finishes (set it to 1 for a process per job; jobs handed to a dedicated worker, and the worker's own init and periodic scripts, do not count). Not counting the init and periodic scripts means they run again on every restart: an init script's runtime is added to the latency of every batch of that many jobs, and a periodic script fires once per process start whatever its interval says. The worker's shell in the workers page also starts backed off rather than after the two minutes it otherwise takes, since a process due to be recycled cannot count on living that long: the first command of a session can wait up to 15s, later ones are immediate. For deployments that isolate executions by process lifetime rather than with nsjail; note that a container restart resets the process, not the container filesystem, so caches and /tmp survive it. The worker name is then derived from the hostname instead of being random, so the restarted worker keeps its row in the workers list (an agent worker keeps the row but restarts its job count). Use one worker per process: workers of one process share its environment, so the first to reach the limit shuts the others down too. |
Worker |
| WORKER_SUFFIX | None | Pins the last part of the worker name, which is otherwise random, so that a restarted worker keeps its row in the workers list. Only needed when several worker processes of the same worker group run on one host, since the name is derived from the hostname: give each of them a distinct value, as two processes sharing one must never happen. At most 64 letters, digits and underscores; anything else is refused at startup. | Worker |
| LICENSE_KEY (EE only) | None | License key checked at startup for the Enterprise Edition of Windmill | Worker |
| SLACK_SIGNING_SECRET | None | The signing secret of your Slack app. See Slack documentation | Server |
| COOKIE_DOMAIN | None | The domain of the cookie. If not set, the cookie will be set by the browser based on the full origin | Server |
| DENO_PATH | /usr/bin/deno | The path to the deno binary. | Worker |
| PYTHON_PATH | The path to the python binary if wanting to not have it managed by uv. | Worker | |
| GO_PATH | /usr/bin/go | The path to the go binary. | Worker |
| GOPRIVATE | The GOPRIVATE env variable to use private go modules | Worker | |
| GOPROXY | The GOPROXY env variable to use | Worker | |
| NETRC | The netrc content to use a private go registry | Worker | |
| PY_CONCURRENT_DOWNLOADS | 20 | Sets the maximum number of in-flight concurrent python downloads that windmill will perform at any given time. | Worker |
| PATH | None | The path environment variable, usually inherited | Worker |
| HOME | None | The home directory to use for Go and Bash , usually inherited | Worker |
| DATABASE_CONNECTIONS | 50 (Server)/3 (Worker) | The max number of connections in the database connection pool | All |
| SUPERADMIN_SECRET | None | A token that would let the caller act as a virtual superadmin superadmin@windmill.dev | Server |
| TIMEOUT_WAIT_RESULT | 20 | The number of seconds to wait before timeout on the 'run_wait_result' endpoint | Worker |
| QUEUE_LIMIT_WAIT_RESULT | None | The number of max jobs in the queue before rejecting immediately the request in 'run_wait_result' endpoint. Takes precedence on the query arg. If none is specified, there are no limit. | Worker |
| DENO_AUTH_TOKENS | None | Custom DENO_AUTH_TOKENS to pass to worker to allow the use of private modules | Worker |
| DISABLE_RESPONSE_LOGS | false | Disable response logs | Server |
| CREATE_WORKSPACE_REQUIRE_SUPERADMIN | true | If true, only superadmins can create new workspaces | Server |
| MIN_FREE_DISK_SPACE_MB | 15000 | Minimum amount of free space on worker. Sends critical alert if worker has less free space. | Worker |
| RUN_UPDATE_CA_CERTIFICATE_AT_START | false | If true, runs CA certificate update command at startup before other initialization | All |
| RUN_UPDATE_CA_CERTIFICATE_PATH | /usr/sbin/update-ca-certificates | Path to the CA certificate update command/script to run when RUN_UPDATE_CA_CERTIFICATE_AT_START is true | All |
Run a local dev setup
We recommend using Nix. See ./frontend/README_DEV.md for all options.
Frontend only
Uses the backend of https://app.windmill.dev with local frontend (hot-reload):
cd frontend
npm install
npm run generate-backend-client # or generate-backend-client-mac on Mac
npm run dev
Windmill available at http://localhost/
Backend + Frontend
See the ./frontend/README_DEV.md file for all running options.
- Start a local Postgres database using for instance the
start-dev-db.shscript which will make a database available atpostgres://postgres:changeme@localhost:5432/windmillThen run the migrations using the following command:This will also avoid compile time issue with sqlx'scargo install sqlx-cli env DATABASE_URL=<YOUR_DATABASE_URL> sqlx migrate runquery!macro. - (optional, linux only) Install nsjail and have it accessible in your PATH
- Install bun, deno and python3 (+ any languages you want to use), have the bins at
/usr/bin/bun,/usr/bin/deno, and/usr/local/bin/python3or set the corresponding environment variables. - (optional) Install the lld linker
- Go to
frontend/:npm install,npm run generate-backend-clientthenREMOTE=http://localhost:8000 npm run dev- You might need to set some extra heap space for the node runtime
export NODE_OPTIONS="--max-old-space-size=4096" - Create an empty
frontend/buildfolder usingmkdir frontend/build
- Go to
backend/:env DATABASE_URL=<YOUR_DATABASE_URL> RUST_LOG=info cargo run- You can specify any feature flag you want to enable, for example
cargo run --features pythonto enable the python executor.
- Windmill should be available at
http://localhost:3000
Contributors
Copyright
© 2023-2026 Windmill Labs, Inc.






