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Jina banner

An easier way to build neural search in the cloud

Jina Python 3.7 3.8 PyPI Docker Image Version (latest semver) CI CD codecov
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Jina is a deep learning-powered search framework for building cross-/multi-modal search systems (e.g. text, images, video, audio) in the cloud.

⏱️ Time Saver - Bootstrap an AI-powered system in just a few minutes.

🧠 First-Class AI Models - The design pattern for neural search systems, with first-class support for state-of-the-art AI models.

🌌 Universal Search - Large-scale indexing and querying of any kind of data on multiple platforms: video, image, long/short text, music, source code, etc.

☁️ Cloud Ready - Decentralized architecture with cloud-native features out-of-the-box: containerization, microservice, scaling, sharding, async IO, REST, gRPC.

🧩 Plug & Play - Easily extendable with Pythonic interface.

❤️ Made with Love - Quality first, never compromises, maintained by a full-time, venture-backed team.

Hello WorldQuick StartLearnContributeJobsWebsiteSlack


On Linux/macOS with Python 3.7/3.8:

pip install -U jina

To install Jina with extra dependencies, or install on Raspberry Pi please refer to the documentation. Windows users can use Jina via the Windows Subsystem for Linux. We welcome the community to help us with native Windows support.

In a Docker Container

Our universal Docker image supports multiple architectures (including x64, x86, arm-64/v7/v6). They are ready-to-use:

docker run jinaai/jina --help

Jina "Hello, World!" 👋🌍

Just starting out? Try Jina's "Hello, World" - a simple image neural search demo for Fashion-MNIST. No extra dependencies needed, simply run:

jina hello-world

...or even easier for Docker users, no install required:

docker run -v "$(pwd)/j:/j" jinaai/jina hello-world --workdir /j && open j/hello-world.html  
# replace "open" with "xdg-open" on Linux
Click here to see console output

hello world console output

This downloads the Fashion-MNIST training and test dataset and tells Jina to index 60,000 images from the training set. Then it randomly samples images from the test set as queries and asks Jina to retrieve relevant results. The whole process takes about 1 minute, and after running opens a webpage and shows results:

Jina banner

Intrigued? Play with different options:

jina hello-world --help

Get Started


Jina provides a high-level Flow API to simplify building search/index workflows. To create a new Flow:

from jina import Flow
f = Flow().add()

This creates a simple Flow with one Pod. You can chain multiple .add()s in a single Flow.


To visualize the Flow, simply chain it with .plot(). If you are using a Jupyter notebook, it will render a flowchart inline:


Gateway is the entrypoint of the Flow.

Feed Data

Let's create some random data and index it:

from jina import Document

with Flow().add() as f:
    f.index_ndarray(numpy.random.random[4,2], output_fn=print)  # index ndarray data, document sliced on first dimension
    f.index_lines(['hello world!', 'goodbye world!'])  # index textual data, each element is a document
    f.index_files(['/tmp/*.mp4', '/tmp/*.pdf'])  # index files and wildcard globs, each file is a document
    f.index((Document() for _ in range(10)))  # index raw Jina Documents

To use a Flow, open it using the with context manager, like you would a file in Python. You can call index and search with nearly all types of data. The whole data stream is asynchronous and efficient.

Fetch Result

Once a request is done, callback functions are fired. Jina Flow implements Promise-like interface, you can add callback functions on_error, on_always to hook different event. In the example below, our Flow passes the message then prints the result when success. If something wrong, it beeps. Finally, the result is written to output.txt.

def beep(*args):
    # make a beep sound
    import os
    os.system('echo -n "\a";')

with Flow().add() as f, open('output.txt', 'w') as fp:
            on_error=beep, on_always=fp.write)

Add Logic

To add logic to the Flow, use the uses parameter to attach a Pod with an Executor. uses accepts multiple value types including class name, Docker image, (inline) YAML or built-in shortcut.

f = (Flow().add(uses='MyBertEncoder')  # class name of a Jina Executor
           .add(uses='jinahub/pretrained-cnn:latest')  # Dockerized Jina Pod
           .add(uses='myencoder.yaml')  # YAML serialization of a Jina Executor
           .add(uses='!WaveletTransformer | {freq: 20}')  # inline YAML config
           .add(uses='_pass'))  # built-in shortcut executor

The power of Jina lies in its decentralized architecture: each add creates a new Pod, and these Pods can be run as a local thread/process, a remote process, inside a Docker container, or even inside a remote Docker container.

Inter & Intra Parallelism

Chaining .add()s creates a sequential Flow. For parallelism, use the needs parameter:

f = (Flow().add(name='p1', needs='gateway')
           .add(name='p2', needs='gateway')
           .add(name='p3', needs='gateway')
           .needs(['p1','p2', 'p3'], name='r1').plot())

p1, p2, p3 now subscribe to Gateway and conduct their work in parallel. The last .needs() blocks all Pods until they finish their work. Note: parallelism can also be performed inside a Pod using parallel:

f = (Flow().add(name='p1', needs='gateway')
           .add(name='p2', needs='gateway')
           .add(name='p3', parallel=3)
           .needs(['p1','p3'], name='r1').plot())

That's all you need to know for understanding the magic behind hello-world. Now let's dive into it!

Breakdown of hello-world

Customize Encoder

Let's first build a naive image encoder that embeds images into vectors using an orthogonal projection. To do this, we simply inherit from BaseImageEncoder: a base class from the jina.executors.encoders module. We then override its __init__() and encode() methods.

import numpy as np
from jina.executors.encoders import BaseImageEncoder

class MyEncoder(BaseImageEncoder):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        H = np.random.rand(784, 64)
        u, s, vh = np.linalg.svd(H, full_matrices=False)
        self.oth_mat = u @ vh

    def encode(self, data: 'np.ndarray', *args, **kwargs):
        return (data.reshape([-1, 784]) / 255) @ self.oth_mat

Jina provides a family of Executor classes, which summarize frequently-used algorithmic components in neural search. This family consists of encoders, indexers, crafters, evaluators, and classifiers, each with a well-designed interface. You can find the list of all 107 built-in executors here. If they don't meet your needs, inheriting from one of them is the easiest way to bootstrap your own Executor. Simply use our Jina Hub CLI:

pip install jina[hub] && jina hub new

Test Encoder in Flow

Let's test our encoder in the Flow with some synthetic data:

def validate(docs):
    assert len(docs) == 100
    assert NdArray(docs[0].embedding).value.shape == (64,)

f = Flow().add(uses='MyEncoder')

with f:
    f.index_ndarray(np.random.random([100, 28, 28]), output_fn=validate, callback_on='docs')

All good! Now our validate function confirms that all one hundred 28x28 synthetic images have been embedded into 100x64 vectors.

Parallelism & Batching

By setting a larger input, you can play with batch_size and parallel:

f = Flow().add(uses='MyEncoder', parallel=10)

with f:
    f.index_ndarray(np.random.random([60000, 28, 28]), batch_size=1024)

Add Data Indexer

Now we need to add an indexer to store all the embeddings and the image for later retrieval. Jina provides a simple numpy-powered vector indexer NumpyIndexer, and a key-value indexer BinaryPbIndexer. We can combine them in a single YAML file:

  - !NumpyIndexer
      index_filename: vec.gz
  - !BinaryPbIndexer
      index_filename: chunk.gz
  workspace: ./
  • ! tags a structure with a class name
  • with defines arguments for initializing this class object.

Essentially, the above YAML config is equivalent to the following Python code:

from jina.executors.indexers.vector import NumpyIndexer
from jina.exeuctors.indexers.keyvalue import BinaryPbIndexer

a = NumpyIndexer(index_filename='vec.gz')
b = BinaryPbIndexer(index_filename='vec.gz')
c = CompoundIndexer()
c.components = lambda: [a, b]

Compose Flow in Python/YAML

Now let's add our indexer YAML file to the Flow with .add(uses=). Let's also add two shards to the indexer to improve its scalability:

f = Flow().add(uses='MyEncoder', parallel=2).add(uses='myindexer.yml', shards=2, separated_workspace=True).plot()

When you have many arguments, constructing a Flow in Python can get cumbersome. In that case, you can simply move all arguments into one flow.yml:

    uses: MyEncoder
    parallel: 2
    uses: myindexer.yml
    shards: 2
    separated_workspace: true

And then load it in Python:

f = Flow.load_config('flow.yml')

Search via Query Flow

Querying a Flow is similar to what we did with indexing. Simply load the query Flow and switch from f.index to Say you want to retrieve the top 50 documents that are similar to your query and then plot them in HTML:

f = Flow.load_config('flows/query.yml')
with f:
    f.search_ndarray(shuffle=True, size=128, output_fn=plot_in_html, top_k=50)

REST Interface of Query Flow

In practice, the query Flow and the client (i.e. data sender) are often physically seperated. Moreover, the client may prefer to use a REST API rather than gRPC when querying. You can set port_expose to a public port and turn on REST support with rest_api=True:

f = Flow(port_expose=45678, rest_api=True)

with f:

That is the essense behind jina hello-world. It is merely a taste of what Jina can do. We’re really excited to see what you do with Jina! You can easily create a Jina project from templates with one terminal command:

pip install jina[hub] && jina hub new --type app

This creates a Python entrypoint, YAML configs and a Dockerfile. You can start from there.


Jina 101 Concept Illustration Book, Copyright by Jina AI Limited   

Jina 101: First Things to Learn About Jina

  English日本語FrançaisPortuguêsDeutschРусский язык中文عربية

Build Your Search App

Get started with neural search, inputs, outputs, and Flows

Tutorials Readings

My First Search App

Beginners tutorial: Search Star Trek script data

Image Search

Image to image search Pokémon sprites with Google's BiT model

Audio Search

Audio to audio search with Vggish model

What is Neural Search?

What it is, how it works, and how it's different

Primitive Data Types in Neural Search System

Construct your first `Document` in Jina

Jina's Layers of Abstraction

Why do we build Jina and for whom?

Curated List of Neural Search and Jina

Comprehensive round-up on Jina tech, concepts

Search with QueryLanguage

Filter search results by category

NLP Semantic Search with Transformers

Dig into Flows and Pods

Flow API: Compose Your Jina Workflow

With Python, YAML, or graphical Dashboard

Input and Output Functions

Data goes in, data comes out. Here's how

Level Up Your Search App

Client-server, scaling, containerization, Docker, and more

Tutorials Readings

Client-Server Architecture

Refactor hello-world into client-server architecture

Scale Up and Speed Up

Scale up Pods to speed up your search and add a customized executor

Workflow Insights in Dashboard

Log and monitor with Jina's graphical Dashboard

Distribute Your Workflow Remotely

Run Pods remotely via console, Jina Gateway, or Flow API

Jina in Docker

Build your Pod into a Docker image: How and why

Want to read more? Check our Founder Han Xiao's blog and our official blog.


Apart from the learning resources we provided above, We highly recommended you go through our documentation to master Jina.

Our docs are built on every push, merge, and release of Jina's master branch. Documentation for older versions is archived here.

Are you a "Doc"-star? Join us! We welcome all kinds of improvements on the documentation.


We welcome all kinds of contributions from the open-source community, individuals and partners. We owe our success to your active involvement.


All Contributors


  • Code of conduct - play nicely with the Jina community
  • Slack workspace - join #general on our Slack to meet the team and ask questions
  • YouTube channel - subscribe to the latest video tutorials, release demos, webinars and presentations.
  • LinkedIn - get to know Jina AI as a company and find job opportunities
  • Twitter Follow - follow and interact with us using hashtag #JinaSearch
  • Company - know more about our company and how we are fully committed to open-source.

Open Governance

GitHub milestones lay out the path to Jina's future improvements.

As part of our open governance model, we host Jina's Engineering All Hands in public. This Zoom meeting recurs monthly on the second Tuesday of each month, at 14:00-15:30 (CET). Everyone can join in via the following calendar invite.

The meeting will also be live-streamed and later published to our YouTube channel.

Join Us

Jina is an open-source project. We are hiring full-stack developers, evangelists, and PMs to build the next neural search ecosystem in open source.


Copyright (c) 2020 Jina AI Limited. All rights reserved.

Jina is licensed under the Apache License, Version 2.0. See LICENSE for the full license text.

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